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:
Motor neurons are divided into ____ groups.\Question: Choose the right answer from options given a) two b) six c) seven d) eight

Ex Output:
a


Ex Input:
Electrolytic capacitors have a useful life of about ____ years.\Question: Choose the right answer from options given a) ten b) eight c) zero d) seven

Ex Output:
a


Ex Input:
Sleep apnea is defined as a greater than ____ second pause in respiration during sleep.\Question: Choose the right answer from options given a) ten b) nine c) seven d) five

Ex Output:

a