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:
Millipedes have ____ pairs of legs on each body segment.\Question: Choose the right answer from options given a) seven b) ten c) six d) two

Ex Output:
d


Ex Input:
Ants have six legs, and each leg has ____ joints.\Question: Choose the right answer from options given a) nine b) zero c) two d) three

Ex Output:
d


Ex Input:
Human insulin consists of ____ different peptide chains.\Question: Choose the right answer from options given a) two b) ten c) three d) one

Ex Output:

a