Two things, swapped

The 2-polar-nuclei fact in Reason R is real — the embryo sac does carry two polar nuclei, which is exactly why a mature sac ends up with one more nucleus (8) than it has cells (7). The mix-up is which part of the sac they belong to: R files them under the egg apparatus, but the egg apparatus is specifically the egg cell plus its two synergids — three cells, three nuclei, no polar nuclei among them. The polar nuclei actually belong to the central cell, the sac's other major component, sitting right next to the egg apparatus in every embryo-sac diagram. Believing R's version still makes it look like a fine explanation for Assertion A's 7-cell/8-nucleus count.

The angle is right — 30° is exactly the angle of refraction at Brewster's incidence — which is what makes this option so tempting: it gets the geometry correct and only trips on which beam ends up completely polarised. At Brewster's angle it's the reflected ray (at ~60°) that's fully polarised, because the reflected and refracted rays end up perpendicular to each other, and that geometry is what filters the reflected light down to one vibration direction. The transmitted ray still carries both directions, just unevenly — it's only ever partially polarised.

Getting "analogy" right is the easy half — sweet potato and potato look alike and store food despite coming from different organs (a root and a stem), which is the textbook definition of analogous structures. The trap is the second word: "divergent" sounds like exactly the right term for "structures that started from different origins," since the two organs genuinely diverged from each other. But divergent evolution names the opposite pattern — one common origin producing different structures, like Darwin's finches — while different origins converging on a similar form and function is convergent evolution. The word that sounds like it should pair with "different origins" is the wrong half of the pair.

Statement II is straightforwardly true — angiosperms have xylem vessels, gymnosperms don't — and that correctness makes it easy to wave Statement I through alongside it. But collenchyma and sclerenchyma are the pair actually being mixed up: collenchyma is a living simple tissue that keeps its protoplasm and can go on dividing, while sclerenchyma is the dead, lignified one. Statement I borrows sclerenchyma's defining trait and hangs it on collenchyma.

Dedifferentiation and redifferentiation name two steps of the same short NCERT sentence in opposite order, which is exactly why they're easy to swap: dedifferentiation is mature, already-specialised parenchyma cells regaining the ability to divide (forming things like interfascicular cambium); redifferentiation is what the new tissue those dividing cells produce does next, as it specialises into xylem, phloem or cork. The question describes fully developed parenchyma cells turning back into a dividing tissue — that reversal is the "de-", not the "re-".

Every name in this option is correct — POCl${}_3$ and $H_3$PO${}_3$ are exactly the two byproducts this pair of reactions makes. What's swapped is which reagent gets which one: PCl${}_3$ with an alcohol gives the alkyl chloride plus phosphorous acid, $H_3$PO${}_3(aP$–H bond survives); PCl${}_5$ gives the alkyl chloride plus HCl plus phosphoryl chloride, POCl${}_3$. This option assigns POCl${}_3$ to the PCl${}_3$ reaction and $H_3$PO${}_3$ to the PCl${}_5$ reaction — the exact reverse of the real pairing.

Reason R, read on its own, is entirely correct — growing follicles do secrete oestrogen, and interstitial (Leydig) cells do secrete androgen. Because R is so clearly right, it's tempting to accept Assertion A as right too and call R its explanation. But A pairs FSH with Leydig cells, and that pairing is the mix-up: FSH acts on the Sertoli cells that nurse the developing sperm, while LH (ICSH) is the hormone that acts on Leydig cells. R's truth about who-secretes-what doesn't rescue A's wrong who-acts-on-whom.

Statement I is safely true — mitochondria and chloroplasts are both double-membrane organelles, a fact drilled early and rarely disputed. That confidence carries over to Statement II, which sounds like the same kind of settled fact: "one membrane is less permeable than the other." The direction is what's swapped — it's the chloroplast's inner membrane that's the less permeable one, not the mitochondrion's — and nothing about how Statement I reads warns you which organelle the rule actually favours.

Endarch and exarch are real, correctly-named terms — Statement I doesn't invent anything, it just files them under the wrong member of the primary/secondary xylem pair that NCERT teaches in the same breath. They describe the position of protoxylem in primary xylem, not secondary xylem as this statement claims, and "primary" and "secondary" growth sit close enough together in the same chapter that the substitution is easy to miss. Statement II, that roots are exarch, is independently true, and its correctness makes it easy to also wave Statement I through rather than checking which growth stage endarch and exarch actually describe.

Statement II, that adult haemoglobin is ${\alpha }_2{\beta }_2$, is straightforwardly true, and its correctness makes it easy to also accept Statement I alongside it without a second look. But Statement I has the protein-chain convention exactly backwards: by convention the first amino acid — drawn on the left — is the N-terminal end, and the last one, on the right, is the C-terminal end. This statement swaps the two, putting the C-terminal on the left and the N-terminal on the right, the reverse of the labelling every peptide-chain diagram uses.

Statement II gets the eukaryotic version of this fact right — DNA is negatively charged, wrapped around positively charged histones — and its correctness makes Statement I's version, sitting right next to it, feel like it should follow the same pattern. It doesn't: Statement I has the charges on the prokaryotic DNA–protein pair backwards, describing the DNA itself as positively charged and the proteins holding it as negative. DNA carries the same negative charge in prokaryotes as it does in eukaryotes; it's the nucleoid proteins that are positively charged — the exact mirror of what this statement says, with the two charges correctly assigned in Statement II but crossed onto the wrong partner in Statement I.