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: COUNTRY CLUBS 
Clue: The 8-member club formed by this treaty shutskied its doors in 1991

SOLUTION: the warsaw pact

PROBLEM: Category: AIRLINE AD SLOGANS 
Clue: "The world's favourite airline"

SOLUTION: british airways

PROBLEM: Category: MOUNTAINS 
Clue: This mountain has additional named peaks that exceed 24,000 feet, including Lhotse & Changtse

SOLUTION:
mount everest