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: HOLIDAYS AND OBSERVANCES 
Clue: The name of this Jewish holy day means "beginning of the year"
[EX A]: rosh hashanah

[EX Q]: Category: SUN 
Clue: In the main reaction making the sun's energy, 2 of these nuclear particles fuse & one becomes a neutron
[EX A]: protons

[EX Q]: Category: GEOGRAPHICAL QUOTES 
Clue: John H. Wilson called it "At once London's highroad and its sewer"
[EX A]:
the thames river