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: ON THE ROCKS 
Clue: This rock formed from hardened lava formed the Hawaiian Islands

SOLUTION: basalt

PROBLEM: Category: THE 19th CENTURY 
Clue: In 1825 patriots crossed the Rio de la Plata from Argentina to fight for this country's freedom from Brazil

SOLUTION: uruguay

PROBLEM: Category: WALTER WORLD 
Clue: One of his novels includes the line "Ye maun Ken, the laird there bought a' thir beasts frae me to munt his troop"

SOLUTION:
sir walter scott