I was taking a Wonderlic test and got somewhat confused by one of the questions. The question was:
CREDIBLE CREDULOUS - Do these words...
 Have similar meanings
 Have contradictory meanings
 Have unrelated meanings
Now, I do know the definition of each word. Credible means trustworthy, easily believed by others. Credulous means gullible, easily believes others. But are these meanings similar (both have to do with one person believing another) or opposite (everyone believes you vs you believe everyone)? I feel like either answer could be easily argued both for and against, but as a non-native English speaker maybe I'm just missing something. They are neither synonyms nor antonyms, so what's the best answer?