With reference to India’s biodiversity Ceylon frogmouth, Coppersmith barbet, Gray-chinned minivet and White-throated redstart are

All four names belong to birds. The Ceylon frogmouth is a nocturnal insectivore with a wide, flat bill and camouflaged plumage. The coppersmith barbet is known for its repetitive, metronome-like call. The gray-chinned minivet is a small, brightly coloured forest bird that moves in flocks. The white-throated redstart is a Himalayan bird that breeds at high altitude. So the answer is A.

Why the others fail:

• Primates are mammals such as the lion-tailed macaque and Nilgiri langur, and none of the four is a primate.
• Reptiles are scaly, cold-blooded animals such as monitor lizards, turtles and snakes.
• Amphibians are moist-skinned animals such as frogs and caecilians. The purple frog of the Western Ghats, described in 2003, is an example, but it is not a bird.

Core concept: the defining features of the vertebrate classes. This is basic for biodiversity questions and links to Western Ghats and Himalayan endemism in Mains GS-III. Most of these birds are protected under the Wildlife (Protection) Act, 1972.

Trap: Candidates try to identify each species and get stuck on the unfamiliar names. The question only asks for the class, and the class can be read off the name itself.