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:
Carbon forms ____ bonds.\Question: Choose the right answer from options given a) five b) four c) two d) three

Ex Output:
b


Ex Input:
Nymphs feed and mature through five instars in about ____ to eight weeks.\Question: Choose the right answer from options given a) six b) five c) seven d) zero

Ex Output:
a


Ex Input:
Cattails contain ____ times the starch of an equal weight fo potatoes.\Question: Choose the right answer from options given a) six b) ten c) eight d) two

Ex Output:

b