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: PRESIDENTS 
Clue: Under an act passed in 1958, they became the first two former presidents eligible for a pension
harry s. truman & herbert hoover

Category: OPERA 
Clue: This 20th century opera was inspired by Hieronymus Bosch's painting "The Adoration of the Magi"
amahl and the night visitors

Category: MUSIC WORDS 
Clue: Before it acquired its musical meaning in the early 20th century, it was baseball slang for "pep" or "energy"

jazz