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').

Q: 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

A: a
****
Q: Food chains consist of ____ trophic levels.\Question: Choose the right answer from options given a) ten b) three c) one d) four

A: d
****
Q: New shoes help keep their feet fresh, and they change socks and shoes ____ times a day.\Question: Choose the right answer from options given a) three b) ten c) nine d) five

A:
a
****