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: 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
Example Output: a

Example Input: Mosquitoes have ____ distinctive life stages, with the first three stages being spent in the water.\Question: Choose the right answer from options given a) four b) zero c) nine d) five
Example Output: a

Example Input: Pups stay in the burrows for about ____ or seven weeks.\Question: Choose the right answer from options given a) six b) four c) eight d) zero
Example Output:
a