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:
Most internal parasites are specific to one or ____ species.\Question: Choose the right answer from options given a) seven b) three c) two d) five

Ex Output:
c


Ex Input:
Genetic mapping divides the chromosomes in ____ bands.\Question: Choose the right answer from options given a) ten b) two c) four d) nine

Ex Output:
b


Ex Input:
Gases inhibit microorganisms by ____ mechanisms.\Question: Choose the right answer from options given a) two b) no c) zero d) six

Ex Output:

a