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:
Ammonia is among the ____ most abundantly produced chemicals in the world.\Question: Choose the right answer from options given a) five b) zero c) no d) eight

Ex Output:
a


Ex Input:
Voles are prolific breeders and can produce four to ____ litters a year.\Question: Choose the right answer from options given a) four b) two c) six d) three

Ex Output:
c


Ex Input:
Carbohydrates come in ____ main types, simple and complex.\Question: Choose the right answer from options given a) zero b) two c) ten d) nine

Ex Output:

b