2023 CSAT — Q23

Locate. This asks for the best-supported inference: it must be entailed, with qualifiers intact. The passage is a list of ecosystem services elephants provide: they create clearings, prevent overgrowth, allow other plants to regenerate, propagate seeds, fertilise via dung, and dig water holes that benefit other wildlife. The entailed claim: elephants are a keystone species that benefits biodiversity.

Test (find-the-line-then-match + qualifier check). (b) “elephants are the keystone species and they benefit the biodiversity” matches every line at the passage’s own strength — describing a beneficial, enabling role. Now test the qualifiers on the others: (c) “rich biodiversity cannot be maintained without elephants” upgrades “benefits” into an absolute necessity the passage never asserts; (a) “the home range of elephants needs to be a vast area of rich biodiversity” reverses the dependence (the passage says the forest benefits from the elephant, not that the elephant requires a rich forest); (d) “capable of regenerating forests with species as per their requirement” claims deliberate, on-demand engineering the passage doesn’t support.

Eliminate by anatomy. (c) is too strong for what the passage says — “cannot be maintained without” is an absolute against a descriptive passage; (a) gets the direction backwards — it flips who-benefits-from-whom; (d) is too strong for what the passage says — “as per their requirement” imputes intentional regeneration. The transferable rule on best-inference questions: the keyed inference keeps the passage’s strength and direction; the plants either inflate “benefits” into “indispensable” or reverse the dependency. Key: (b).

The passage describes elephants creating clearings, preventing overgrowth, allowing regeneration of other plants, propagating seeds, enriching soil via dung, and digging water holes “which benefits other wildlife.” Every line shows elephants enabling and benefiting the wider ecosystem — i.e. a keystone species that benefits biodiversity — exactly (b). (c) over-strengthens this into “cannot be maintained without” (absolute); (a) reverses the dependence (the forest needs the elephant, not the elephant a rich forest); (d) over-claims deliberate, on-demand regeneration → (b).

The passage enumerates elephants’ ecosystem services — clearings, controlled overgrowth, seed dispersal, soil nourishment, water access for other wildlife. The fair inference is that elephants are a keystone species benefiting biodiversity.

(b) states exactly that, at the passage’s strength. (c) over-strengthens to “cannot be maintained without,” an absolute the passage never claims. (a) reverses the dependence (the forest needs the elephant, not the elephant a rich-biodiversity range). (d) over-claims deliberate regeneration “as per their requirement.”

Answer: (b).

All four options are about the right relationship — elephants and ecosystem health — and three fail on a single word of strength or direction. (c) inflates “benefits” to “cannot survive without”; (a) reverses who benefits; (d) adds purposeful control. (b) alone keeps the passage’s qualifier — a keystone species that benefits biodiversity, no more. On best-inference questions, the difference between the key and the trap is almost always one quantifier or one arrow. (b).