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.

Category: SOCIAL SCIENCE 
Clue: It's the study of the principles of punishment as well as the management of prisons
penology

Category: JUILLIARD ALUMNI 
Clue: Not averse to portraying icons, this alum has played Jim Morrison, Elvis Presley & Batman on film
val kilmer

Category: O PIONEERS! 
Clue: In treeless areas, pioneers built houses of this 3-letter material, filling cracks with mud; hey, it was dirt cheap!

sod