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: THE ROTARY CLUB 
Clue: On an airplane they're "fixed"; on a helicopter they're actually "rotary"

SOLUTION: wings

PROBLEM: Category: "HO" 
Clue: In this process the fat molecules in milk are broken up into very fine particles

SOLUTION: homogenization

PROBLEM: Category: PSYCHOLOGY 
Clue: Behaviorist Clark Hull reduced motivations to needs like hunger, which he gave this "transporting" term

SOLUTION:
drives