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:
Elk retain their antlers for more than ____ months of the year.\Question: Choose the right answer from options given a) nine b) ten c) six d) seven

Ex Output:
c


Ex Input:
Many tractors have ____ wheel drive to get extra grip on the hills and in wet conditions.\Question: Choose the right answer from options given a) four b) seven c) five d) two

Ex Output:
a


Ex Input:
Bacterial cells outnumber human cells ten to ____ .\Question: Choose the right answer from options given a) three b) seven c) zero d) one

Ex Output:

d