instruction:
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.
question:
Category: FORWARDS & BACK WORDS 
Clue: To boast & clothing
answer:
brag & garb


question:
Category: A WALK ACROSS THE CHARLES BRIDGE 
Clue: Originally called Stone Bridge, the Charles Bridge was built with this "stone", like the walls of the White House
answer:
sandstone


question:
Category: SPIES 
Clue: This American spy was exchanged for Rudolf Abel on February 10, 1962
answer:

powers