Correct answer: (d) 1, 2, 3 and 4
Explanation
- A
1 and 3 only
(a) 1 and 3 only. Green turtles and dugongs/manatees show that some turtles and some marine mammals are herbivores, but herbivorous fishes and viviparous snakes are also true, so stopping at 1 and 3 is not the key.
- B
2, 3 and 4 only
(b) 2, 3 and 4 only. Those three hold, but statement 1 also holds, so dropping turtles is not the key.
- C
2 and 4 only
(c) 2 and 4 only. Incomplete relative to all four true claims, so not the key.
- D
1, 2, 3 and 4
(d) 1, 2, 3 and 4. Some turtles are herbivores (adult green turtle). Many fishes graze algae or plants. Sirenians are marine-mammal herbivores. Boas, vipers and sea snakes include viviparous (or ovoviviparous) species. All four statements stand, so this is the official key.
Summary. Official key is (d) all four. Herbivory exists among turtles, fishes and marine mammals; live-bearing occurs in several snake groups. None of the four statements is a zoological falsehood on the UPSC key. Honour the stored letter (d).