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').

Example Input: Most people require roughly seven to ____ hours of sleep a night to stay alert through the day.\Question: Choose the right answer from options given a) eight b) ten c) one d) five
Example Output: a

Example Input: Normal cells have ____ copies of each chromosome.\Question: Choose the right answer from options given a) two b) five c) eight d) no
Example Output: a

Example Input: Earthworms range in length from a tiny one millimetre to a massive ____ metres.\Question: Choose the right answer from options given a) eight b) seven c) five d) three
Example Output:
d