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').

Input: Consider Input: Spores have ____ combinations of sexes.\Question: Choose the right answer from options given a) four b) five c) seven d) three

Output: a


Input: Consider Input: Many tortoises can retract their head, their ____ limbs and tail into the shell for protection.\Question: Choose the right answer from options given a) no b) one c) two d) four

Output: d


Input: Consider Input: Bivalves have ____ shells sandwiched together.\Question: Choose the right answer from options given a) two b) five c) eight d) nine


Output: a