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:
Embrasures have ____ functions.\Question: Choose the right answer from options given a) three b) seven c) zero d) nine

Ex Output:
a


Ex Input:
Circles mark the approximate locations of ____ recently discovered solar systems.\Question: Choose the right answer from options given a) four b) no c) zero d) nine

Ex Output:
a


Ex Input:
Scientists divide the Precambrian into ____ eons.\Question: Choose the right answer from options given a) three b) five c) no d) one

Ex Output:

a