Read the text and answer the question by selecting all the correct responses. More than one response is correct.
It ought to be obvious that cetaceans—whales, porpoises, and dolphins—are mammals. They breathe through lungs, not through gills, and give birth to Young’s. Their efficient bodies, the absence of hind legs, and the presence of a fluke1 and blowhole2 cannot disguise their affinities with land-dwelling mammals. However, not like the cases of sea otters and pinnipeds (seals, sea lions, and walruses, whose limbs are functional both on land and at sea), it is not easy to envision what the first whales looked like. Extinct however already fully marine cetaceans are known from the fossil record. How was the gap between a walking mammal and a swimming whale bridged? Missing till recently was fossils clearly intermediate, or transformation, between land mammals and cetaceans.
Q. Which of the following can be inferred from paragraph 1 about early sea otters?
(A) It is not difficult to imagine what they looked like.
(B) There were great numbers of them.
(C) They lived in the sea and land.
(D) They did not leave many fossil remains.