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').

[EX Q]: Electrolytic capacitors have a finite lifetime, usually about ____ years.\Question: Choose the right answer from options given a) zero b) ten c) four d) eight
[EX A]: b

[EX Q]: Some species can make dives over ____ hundred feet deep.\Question: Choose the right answer from options given a) six b) eight c) two d) one
[EX A]: b

[EX Q]: Sound waves travel about four times as fast in water and about ____ times as fast in steel.\Question: Choose the right answer from options given a) zero b) six c) ten d) eight
[EX A]:
c