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').

[Q]: Respiratory therapists complete ____ to four years of education.\Question: Choose the right answer from options given a) one b) nine c) zero d) two
[A]: d


[Q]: Snowflakes are crystals that have many different shapes, but each snowflake has ____ points on it.\Question: Choose the right answer from options given a) six b) nine c) one d) seven
[A]: a


[Q]: Natural copper contains ____ isotopes.\Question: Choose the right answer from options given a) four b) two c) ten d) nine
[A]:
b