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 consistency, answers should be in all lower cased letters.

[Q]: Category: SUCH GOOD CHEMISTRY 
Clue: A U.S. nuclear weapon using this element, Co, has been termed a doomsday device, as it would wipe out life on Earth
[A]: cobalt


[Q]: Category: THE HISTORY OF APRIL 9th 
Clue: 1959: NASA publicly introduces Messrs. Glenn, Shepard & the rest of this program's 7 astronauts
[A]: mercury


[Q]: Category: TV CHIEFS 
Clue: In 1995 this secret agent played by Don Adams was promoted to chief of CONTROL
[A]:
maxwell smart/agent 86