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: GOVERNMENT 
Clue: Under Medicare most Americans this age & over pay a 15% surtax to cover catastrophic illness
65

Category: SOUP ALPHABET 
Clue: "B" is for this thin soup; Swanson's makes beef, chicken & vegetable varieties
broth

Category: GEOLOGY 
Clue: This crater is formed when a volcano explodes & the cone collapses; Oregon's Crater Lake is an example

the caldera