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: ROYALTY 
Clue: It's the name of today's longest-ruling family in Europe, in power for most of the last 711 years

SOLUTION: grimaldi

PROBLEM: Category: TRINIDADIAN AMATEUR ICHTHYOLOGISTS 
Clue: This common aquarium fish was named for a Trinidadian clergyman

SOLUTION: guppy

PROBLEM: Category: LEADING MEN 
Clue: 1 of 2 actors who have earned acting Academy Award nominations in the last 5 consecutive decades

SOLUTION:
jack nicholson or michael caine