Cryptozoology is predicated on a notion that is every bit as _____ as the very quarry it aims to study: one cannot disprove the existence of that which does not exist.
A mysterious
B irrefutable
C cautious
D elusive
E fundamental
官方解释如下:
The concept here is there exists a field that tries to prove the existence of something that does not exist. Just as difficult as trying to catch an animal (notice the 'zoology' in cryptozoology) difficult feat. 'Elusive' works well. It means hard to pin down, something that is always beyond one's grasp.
(A) superficially makes sense. Yet it is too vague.
(B) is a very tempting answer. That said, you can refute the existence of an animal, but you can't refute the animal itself ("irrefutable...very quarry it aims....", does not make any sense).