One wrong clause, hidden in a right list

A, B and C are all confirmed regulators of cardiac activity — nodal tissue sets the rhythm, a medullary neural centre modulates it, adrenal medullary hormones adjust it further — so three-quarters of "all four" is exactly right, and including everything on the list feels like the safe, generous choice. D is the one addition that breaks it: adrenal cortical hormones, named right next to the medullary ones from the same gland, do not regulate cardiac activity at all. One extra clause, borrowed from the wrong part of the same organ, turns a correct set into a wrong one.

C and E are both correct and slightly technical facts — isoelectronic species sharing 18 electrons, caesium's atomic radius genuinely exceeding lithium's and rubidium's — so getting them right builds confidence in the rest of the option. A is the false addition: gallium is actually famous for an unusually low melting point (it can melt in your hand), not a high one, so "unlike Ga, which has a very high melting point" has the comparison backwards from the start. One surprising, easily-misremembered fact is enough to flip an otherwise-correct-sounding option.

A and C are both correctly kept here — auxins do induce parthenocarpy, and dedifferentiation genuinely has to happen before redifferentiation. What gets swapped in is E, "apical dominance promotes the growth of lateral buds," which reads as a plausible, positive-sounding claim about a process named "dominance" — easy to wave through as true. Apical dominance is defined by doing the opposite: the terminal bud suppresses the lateral buds around it, which is the entire point of the term. The clause this option actually needed instead, B (growth regulators can both promote and inhibit growth), is a quieter, more abstract statement that's easy to leave out once E has already filled the "third true fact" slot.

Trichoderma polysporum (C) is correctly flagged here — it's an industrial source of cyclosporin A, not a household name. What sinks this option is pairing it with Saccharomyces cerevisiae (D): yeast used for bread and traditional beverages, exactly the kind of production that also happens at serious industrial scale (breweries, commercial bakeries), which makes it easy to file yeast under "industrial" alongside Trichoderma. NCERT's own household-products list uses Saccharomyces for precisely bread and beverages, though — the actual second industrial-only microbe is Aspergillus niger (citric acid production), not the yeast this option swaps in.

DNA recombinase (D) is correctly caught here — whatever its name suggests, it isn't a real member of the restriction-enzyme/ligase/polymerase cloning toolkit. The mistake is pairing it with DNA polymerase (E), which very much belongs in that toolkit: it's what runs PCR, the amplification step this same explanation credits it for. Picture "gene cloning" narrowly as just cutting with a restriction enzyme and pasting with ligase into a vector, and polymerase's PCR role starts to feel like a separate, skippable technique rather than part of the essential set — which leaves the actual second non-member, DNA mutase (C), uncaught.

A, C and D are all solid, textbook-correct facts about Phaeophyceae — biflagellate zoospores, mannitol/laminarin storage, the chlorophyll a-and-c pigment set — so three-quarters of this option is exactly right. The clause that sinks it is B: sexual reproduction in brown algae isn't oogamous only, it ranges across isogamous, anisogamous and oogamous depending on the genus. That one absolute word turns an otherwise-plausible statement false, and it's easy to let it through on the strength of the true clauses sitting next to it.

A, C, D and E are the complete correct set — this option gets all four of them right, which makes it look like the safe, generous choice: include everything that sounds true. What it adds on top, B, describes a different pattern — alleles that show no dominance at all, with both parental characters appearing together in $F_2$. That's incomplete or co-dominance, not the law of dominance the question is actually asking about, and its presence is what turns a complete answer into an over-complete, wrong one.

A (a liquid evaporating) and D (one gas molecule splitting into two) are both straightforward, disorder-increasing changes, so two-thirds of this option is safely correct. B swaps in a process that runs the entropy argument backwards: cooling a crystalline solid from 130 K toward absolute zero makes the system more ordered, not less, so entropy falls rather than rises. It's the one clause here where "a temperature is changing" gets mistaken for "entropy must be increasing."

Myasthenia gravis and rheumatoid arthritis (A and B) are both genuinely autoimmune, so two of this option's three names are correct out of the gate. The swap is D for E: muscular dystrophy is a genetic, inherited muscle disorder with no immune component, while SLE (systemic lupus erythematosus) — the disorder this option leaves out — is one of the textbook autoimmune diseases. A single one-letter substitution turns a mostly-right list into a wrong one.