Query about question "Beth is not the most _________ pupil, but her..." [4282]

GRE GRE Verbal Problem Solving
1

https://www.gregmat.com/problems/verbal?problem=beth-is-not-the-most-_________-pupil-but-her

why not prodigious?

2

Prodigious has no synonym pair.

3

Prodigious has no synonym pair, apt and astute are not exaggerated enough to be synonyms of prodigious