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:
All quetzals have ____ legs.\Question: Choose the right answer from options given a) four b) zero c) eight d) ten

Ex Output:
a


Ex Input:
Matter exists in ____ forms, solid, fluid and plasma.\Question: Choose the right answer from options given a) ten b) nine c) three d) five

Ex Output:
c


Ex Input:
Psychologists classify memory into the ____ R s - recollection, recall, recognition, and relearning.\Question: Choose the right answer from options given a) three b) no c) four d) seven

Ex Output:

c