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').

Example Input: Babies show an interest in solid foods when they are approximately four to ____ weeks old.\Question: Choose the right answer from options given a) nine b) eight c) five d) six
Example Output: c

Example Input: Conglomerate integration is when ____ apparently unconnected companies merge.\Question: Choose the right answer from options given a) two b) six c) no d) three
Example Output: a

Example Input: Seals swim to the surface to breathe every ____ to fifteen minute.\Question: Choose the right answer from options given a) five b) seven c) six d) zero
Example Output:
a