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 Q]: Fever usually lasts for an average of ____ days in adults.\Question: Choose the right answer from options given a) zero b) three c) nine d) two
[EX A]: b

[EX Q]: Mothers usually give birth to one, two, or ____ babies at a time.\Question: Choose the right answer from options given a) three b) zero c) five d) ten
[EX A]: a

[EX Q]: Older nymphs have ____ black spots on the thorax and one on the abdomen.\Question: Choose the right answer from options given a) two b) four c) three d) zero
[EX A]:
b