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').
--------
Question: Atoms are extremely small, on the order of a few ____ billionths of a meter.\Question: Choose the right answer from options given a) ten b) seven c) nine d) eight

Answer: a


Question: Vaporization can occur in temperatures as low as ____ degrees.\Question: Choose the right answer from options given a) one b) zero c) eight d) two

Answer: b


Question: Plants are divided into ____ broad categories based on their mode of reproduction.\Question: Choose the right answer from options given a) three b) six c) four d) eight

Answer:
c