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]: Reptiles also have scaly skin and a ____ chambered heart.\Question: Choose the right answer from options given a) zero b) one c) ten d) three
[A]: d


[Q]: Every person is a carrier for about ____ rare genetic conditions.\Question: Choose the right answer from options given a) nine b) ten c) six d) three
[A]: b


[Q]: Fertilizer is applied according to soil tests taken every ____ to four years.\Question: Choose the right answer from options given a) four b) seven c) three d) ten
[A]:
c