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.

[Q]: Category: WORLD HISTORY 
Clue: He completed vols. 2 & 3 of Karl Marx's "Das Kapital"
[A]: friedrich engels


[Q]: Category: SIGNS & SIGNALS 
Clue: The ringing of the church bells on this holiday in 1572 was the signal to massacre Huguenots
[A]: st. bartholomew\'s day


[Q]: Category: BILLBOARD'S HOT 100 
Clue: In 2010 they broke the Beatles' record for having had the most songs on the Hot 100 chart by a non-solo act
[A]:
the cast of glee