TASK DEFINITION: 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 simplicity, answers should be in all lower cased letters.
PROBLEM: Category: REMEMBRANCE OF THINGS "CAST" 
Clue: Hey, baby, you a Gemini?  These twin brothers of Helen of Troy are, literally

SOLUTION: castor & pollux

PROBLEM: Category: YOU GET AN "F" 
Clue: These seedless, nonflowering plants reproduce by spores on the undersides of their fronds

SOLUTION: ferns

PROBLEM: Category: INITIAL REACTIONS 
Clue: That is right, it's the abbreviation from the Latin for "that is"

SOLUTION:
i.e.