Read the passage and answer: The mountaineers were exhausted after their grueling ascent. They had climbed for fourteen hours through thin air and freezing temperatures. What does 'grueling' mean in this context?

Vocabulary-in-context questions ask the meaning of a word as used in the passage. Strategy: ignore what the word might mean elsewhere; figure out what it means here. Context clues: (1) Surrounding details — 'exhausted,' 'fourteen hours,' 'thin air and freezing temperatures' all suggest something difficult and tiring; (2) The sentence structure shows 'exhausted after their grueling ascent' — so grueling describes the cause of exhaustion. Definition of grueling: extremely tiring, demanding, exhausting. Distractor analysis: 'easy' opposite meaning; 'quick' doesn't fit (climb took fourteen hours, not quick); 'enjoyable' doesn't fit with exhausted/freezing. Common context clue types: (1) Definition clues — the word is defined directly ('A barometer, an instrument for measuring atmospheric pressure...'); (2) Example clues ('Various reptiles, such as snakes and lizards...'); (3) Synonym clues ('His diligent, hardworking nature...'); (4) Antonym clues ('Unlike his lazy brother, John is industrious'); (5) General context — meaning emerges from overall passage.