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: 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: Electrolytic capacitors have a useful life of about ____ years.\Question: Choose the right answer from options given a) ten b) eight c) zero d) seven
Example Output: a

Example Input: Babies first laugh when they are as young as ____ to four months old.\Question: Choose the right answer from options given a) zero b) nine c) three d) six
Example Output:
c