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:
Brachiopods are superficially similar to bivalves, both having ____ shells.\Question: Choose the right answer from options given a) two b) eight c) seven d) one

Ex Output:
a


Ex Input:
Reality is more than what can be perceived with the ____ senses.\Question: Choose the right answer from options given a) five b) four c) ten d) one

Ex Output:
a


Ex Input:
Laughter first appears around ____ to four months in response to active stimuli.\Question: Choose the right answer from options given a) ten b) three c) four d) one

Ex Output:

b