Boa constrictors have tiny hind leg bones buried in muscles

So If we can prove that the very fragile hind legs and half formed hind leg bones, were NOT remnants of something else, rather remnants of hind legs only, then that is the strongest support for the conclusion.

(A) No other snakes comparable to boa constrictors in size and weight have remnants of hind leg bones : Just because no other snake has remnants of hind legs bones, does not mean The Boa Constrictor could NOT have had hind legs and remnants of those legs .INCORRECT.

(B)No fossils of ancient boa constrictors with intact hind legs capable of sup-porting the animal‖s weight have ever been discovered : Maybe those kind of fossils have yet to be discovered, or maybe those fossils were destroyed or maybe only the legs of those fossils were destroyed.Hence discovering fossils without intact hind legs doesn't prove anything.INCORRECT.

(C) It has not yet been conclusively proved that these vestigial legs of boas are non-functional : So we cannot prove that these legs were non functional, so they did have some use. But were they part of legs or part of tail or part of something else. So just because these legs had some use, we cannot convincingly conclude, that the half formed bones , were remnants of legs.INCORRECT.

(D) Older boa constrictor fossils confirm that ancient boas had full hind leg bones : Older Boa constrictor fossils had full hind leg bones, and later fossils had half formed hind leg bones with very fragile hind legs , so this presents the strongest support that the half formed hind leg bones were remnants of legs that The Boa constrictor once had.CORRECT.

(E) Animals with hind legs would typically also have pelvises and these would be evident in their fossils : Nothing in the passage talks about the fossil having Pelvises or not having Pelvises. irrelevant. INCORRECT.

Hope it's clear.