Given a sentence with a missing word, pick the answer option that best fills out the missing word in the sentence. Indicate each answer with its index ('a', 'b', 'c', 'd').

Youth unemployment is ____ times the adult level.\Question: Choose the right answer from options given a) one b) three c) seven d) no
b

Some olive trees live to be ____ thousand years old.\Question: Choose the right answer from options given a) ten b) zero c) two d) seven
c

Raindrops produce ____ types of sound underwater.\Question: Choose the right answer from options given a) six b) ten c) two d) zero

c