You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For consistency, answers should be in all lower cased letters.

[Q]: Category: THE FORTUNE 500 
Clue: Despite a 57% drop in profits last year, this oil company, No. 2, is still the most profitable co. on the list
[A]: exxon mobil


[Q]: Category: SEX CHANGES 
Clue: Don't let the pearls fool you, these lady bivalves can change into males when it suits them
[A]: oysters


[Q]: Category: THE AMERICAN HERITAGE DICTIONARY, PAGE 1 
Clue: Insect terrorizer seen here
[A]:
aardvark