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: HARRISON FORD 
Clue: 1 of the 4 characters Ford has played more than once on film
han solo, jack ryan, indiana jones or bob

Category: ANTARCTICA 
Clue: A research base at the South Pole is co-named for these 2 explorers, the first 2 to reach it
amundsen

Category: ROBOT MANIA 
Clue: This astromech droid from Naboo met his best bud, a protocol droid, in a sandstorm on Tatooine

r2-d2