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: NATURE STUDY 
Clue: This tall shrub is prized for the reddish dye obtained from its leaves that's used to color hair
henna

Category: YOUR MOMMA! 
Clue: Trojan hero Hector (they share a syllable)
hecuba

Category: PHILOSOPHY 
Clue: This 19th century Danish philosopher was known to his followers as "S.K."

kierkegaard