The rise in the Irrawaddy dolphin (1) in Chilika can be attributed to the…

Concept

In a vocabulary-based cloze blank, the missing word must match the exact sense required by the surrounding sentence, not merely a loosely related meaning. Words that are near-synonyms in isolation (a term for people connected to a place, a term for residents, a term for a kinship group, a term for the total count of a species in an area) often cannot substitute for one another once collocation and register are checked against the specific verbs and phrases around the blank.

Application

The blank sits inside the phrase "the rise in the Irrawaddy dolphin ___ in Chilika". The rest of the passage is reporting a numerical trend for a wildlife species: fish enclosures were removed, freeing movement area, and fewer tourist boats during the COVID-19 lockdown made movement easier between parts of the lake — both are habitat factors that let a species’ numbers grow. "Rise in the ___" therefore needs a word that names a measurable count of a species in a given area, which is exactly what is being tracked here.

• "natives" names people who were born in a place, marking origin/ancestry of persons — it is not used to report a numerical trend for a wildlife species, so "rise in the ... natives" reads as an odd substitution for a statistic.

• "inhabitants" names those who live in or occupy a place at a given time, emphasising residence rather than a rising or falling count — pairing it with "rise in" produces an unnatural, non-idiomatic collocation next to the count-based phrasing the sentence needs.

• "clan" names a group bound by kinship or shared descent, a social/genealogical unit — not a quantity that can numerically "rise", so it does not fit a sentence reporting a statistic.

• "population" names the total count of members of a species living in a given area at a given time, and is the standard word paired with "rise/fall/increase/decrease in" when reporting a numerical change for any species in a habitat — exactly the statistic this sentence is reporting.

Cross-check

Read each option back into the full clause: "the rise in the Irrawaddy dolphin population in Chilika can be attributed to the eviction of ... fish enclosures" reads as a natural, complete statistical statement, while substituting "natives", "inhabitants", or "clan" in the same slot breaks either the collocation with "rise in" or the register of a factual/statistical passage. The fill therefore has to be the word that denotes a measurable species count.