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: WORD ORIGINS 
Clue: Like the name of a minor Roman god, this word for a caretaker comes from the Latin for "door"

SOLUTION: janitor

PROBLEM: Category: CALIFORNIA HISTORY 
Clue: Surname of the employer of James W. Marshall, who found gold in a stream near the Sacramento river in 1848

SOLUTION: sutter

PROBLEM: Category: THE ELEMENTS 
Clue: At its standard mass, it puts the red in red fireworks; its 90 isotope is found in nuclear fallout

SOLUTION:
strontium