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:
Potential energy is divided into ____ different types of energy.\Question: Choose the right answer from options given a) eight b) three c) zero d) two

Ex Output:
b


Ex Input:
Digital bandwidth enables signal to be condensed as a five to ____ ratio.\Question: Choose the right answer from options given a) one b) nine c) seven d) six

Ex Output:
a


Ex Input:
Insects go through ____ stages of change.\Question: Choose the right answer from options given a) five b) two c) one d) three

Ex Output:

d