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:
Metabolism have ____ stages-catabolism and anabolism.\Question: Choose the right answer from options given a) nine b) two c) five d) three

Ex Output:
b


Ex Input:
Summer is the hottest of the ____ temperate seasons , falling between spring and autumn .\Question: Choose the right answer from options given a) six b) four c) no d) nine

Ex Output:
b


Ex Input:
Bolivia has ____ national parks, although most are little known outside the country.\Question: Choose the right answer from options given a) eight b) two c) ten d) zero

Ex Output:

a