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:
Bone marrow replenishes itself fully within ____ weeks.\Question: Choose the right answer from options given a) nine b) no c) one d) two

Ex Output:
d


Ex Input:
Nymphs feed and mature through five instars in about ____ to eight weeks.\Question: Choose the right answer from options given a) six b) five c) seven d) zero

Ex Output:
a


Ex Input:
Many modern roses originate from only eight to ____ wild species.\Question: Choose the right answer from options given a) two b) ten c) four d) one

Ex Output:

b