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.

Category: RED, WHITE OR BLUE 
Clue: Jack London's follow-up doggie tale to "The Call of the Wild"
white fang

Category: RECENTLY DISCOVERED ANCIENT ROMANS 
Clue: This guy, a strong coffee prepared by forcing steam under pressure through ground beans, was quite lively
espresso

Category: ASTRONOMY 
Clue: From 1979 to 1999 it was the planet in our solar system farthest from the sun

neptune