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:
Electrons have almost ____ mass and are negatively charged.\Question: Choose the right answer from options given a) three b) seven c) zero d) no

Ex Output:
d


Ex Input:
Females inherit ____ X chromosomes, one from each parent.\Question: Choose the right answer from options given a) five b) two c) no d) seven

Ex Output:
b


Ex Input:
Umbilical cords separate in ____ to three weeks on average.\Question: Choose the right answer from options given a) six b) three c) two d) eight

Ex Output:

c