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

Water softeners add sodium to drinking water in ____ ways.\Question: Choose the right answer from options given a) zero b) six c) two d) nine
c

Homosexuals have ____ times the rate of alcoholism, drug abuse and suicide as heterosexuals.\Question: Choose the right answer from options given a) ten b) four c) three d) nine

c