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: ART & ARTISTS 
Clue: An X-ray of his "Blue Boy" has revealed the figure of a small dog that was painted out
[A]: thomas gainsborough


[Q]: Category: BIBLICAL QUOTES 
Clue: In Genesis 17:4 God told him, "Thou shalt be a father of many nations"
[A]: abraham


[Q]: Category: COMMIES 
Clue: The Russian word poputchik is this 2-word phrase & describes a type of communist "fellow"
[A]:
fellow traveller