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:
Altimetric satellites are usually limited life missions lasting approximately three to ____ years.\Question: Choose the right answer from options given a) five b) ten c) four d) eight

Ex Output:
b


Ex Input:
Some programming languages have ____ or more standards.\Question: Choose the right answer from options given a) no b) seven c) two d) three

Ex Output:
c


Ex Input:
Skin is made up of ____ distinct layers.\Question: Choose the right answer from options given a) two b) one c) ten d) zero

Ex Output:

a