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:
Black women die from cervical cancer at ____ times the rate of white women.\Question: Choose the right answer from options given a) five b) one c) two d) three

Ex Output:
d


Ex Input:
Aridity presents ____ main obstacles to solitary behavior.\Question: Choose the right answer from options given a) no b) three c) two d) five

Ex Output:
c


Ex Input:
Nitrogen prefers to form three bonds and have ____ lone pair of electrons.\Question: Choose the right answer from options given a) eight b) two c) nine d) one

Ex Output:

d