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: EUROPEAN ARTISTS 
Clue: In 1891 he held an auction of his paintings to finance his move to Tahiti
paul gauguin

Category: THE 1970s 
Clue: In 1977 Bank of America changed the name of its Bank Americard to this 4-letter word
visa

Category: EXPLORERS 
Clue: He served in the Confederate army & the Union navy before hooking up with Livingstone

henry stanley