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 consistency, answers should be in all lower cased letters.

Category: A PARIS CHRONOLOGY 
Clue: Paris was founded around 250 B.C. by the Celtic Parisii tribe, who built a settlement on an island in this river
the seine

Category: THE NEAREST 
Clue: ...of your 4 limbs to your heart is this one
your left arm

Category: THE LIST LIST 
Clue: Number of songs on the American top pop list hosted by Casey Kasem

40