instruction:
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.
question:
Category: FIRST LADIES 
Clue: First Lady in the 1910s, she later rode in President Kennedy's inaugural parade
answer:
edith wilson


question:
Category: MUSIC 
Clue: Webster's defines this word as "a chord of three tones consisting of a root with its third and fifth"
answer:
a triad


question:
Category: MATH 
Clue: When 2 of these intersect, their intersection is a straight line
answer:

a plane