TASK DEFINITION: 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.
PROBLEM: Category: ISLANDS 
Clue: Part of the 4th-most populous country, it's the world's most populous single island with about 120 million people

SOLUTION: java

PROBLEM: Category: PRESIDENTS 
Clue: 2 of the 3 successive presidents who were Republicans, born in Ohio & generals in the Union army

SOLUTION: ulysses s. grant, rutherford b. hayes & james a. garfield

PROBLEM: Category: FAMOUS NAMES 
Clue: A grandson of Man O' War, he defeated his uncle in a famous matchup November 1, 1938

SOLUTION:
seabiscuit