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: Female elephants have babies about ____ years apart, and they have only one each time.\Question: Choose the right answer from options given a) eight b) one c) zero d) three
Example Output: d

Example Input: Mosquitoes have three body parts and ____ legs.\Question: Choose the right answer from options given a) two b) nine c) six d) eight
Example Output: c

Example Input: Most poor families have none, ____ or two children.\Question: Choose the right answer from options given a) one b) three c) six d) nine
Example Output:
a