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.

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

[EX Q]: Category: ARCHITECTS 
Clue: Dallas-Fort Worth Airport architect Gyo Obata helped design this Smithsonian museum
[EX A]: air & space museum

[EX Q]: Category: MUSICAL INSTRUMENT ORIGINS 
Clue: 2 guys in what is now this country were the oom-papas of the tuba, patenting it in 1835
[EX A]:
germany