Solution

The IUCN Red List classifies species by their risk of extinction.
Reptiles such as turtles, tortoises, crocodiles and many lizards and snakes are threatened by habitat loss, hunting for skins, meat and eggs, the pet trade, and their slow reproduction and restricted ranges.
As per the answer key, reptiles are taken as the vertebrate group with the highest number of endangered species.
(The ranking depends on which list and which year is used, and on whether numbers or the proportion of species assessed are compared; in many later assessments amphibians, which are not among the options here, have the highest proportion of threatened species.)
So the answer is reptiles.

Concept Endangered vertebrate groups

Biodiversity and Conservation in past papers

95 questions from this chapter have appeared across 25 exam years.