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: THE NATIONAL TOY HALL OF FAME 
Clue: Initial sales for it were sluggish, but demonstrations of how it walked down stairs at Gimbels made it walk off shelves
[A]: a slinky


[Q]: Category: MR. BODY 
Clue: Fed by the hepatic portal veins, it weighs about a pound more in men than in women
[A]: liver


[Q]: Category: UNIVERSAL TRUTH 
Clue: Observations from this, launched in 1990, revealed galaxies older than astronomers expected
[A]:
the hubble telescope