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').

Ex Input:
Some motors contain ____ gears and spin very fast, and have little if any torque.\Question: Choose the right answer from options given a) four b) three c) five d) no

Ex Output:
d


Ex Input:
Female cats come into heat cycles every ____ to four weeks during certain times of the year.\Question: Choose the right answer from options given a) eight b) ten c) zero d) three

Ex Output:
d


Ex Input:
Botanists currently recognize ____ species of Hevea.\Question: Choose the right answer from options given a) nine b) zero c) two d) seven

Ex Output:

a