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').

Ants have six legs, and each leg has ____ joints.\Question: Choose the right answer from options given a) nine b) zero c) two d) three
d

Infants usually die of pneumonia or other infections before reaching ____ years of age.\Question: Choose the right answer from options given a) nine b) four c) zero d) eight
b

Ticks have ____ legs during their first stage.\Question: Choose the right answer from options given a) one b) six c) five d) two

b