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]: Organisms have ____ forms of nucleic acid.\Question: Choose the right answer from options given a) four b) three c) two d) one
[A]: c


[Q]: Malignant tumors are more dangerous, and survival times can range from ____ months to several years.\Question: Choose the right answer from options given a) one b) no c) ten d) six
[A]: d


[Q]: Negation is a total inverse for all ____ addition operators.\Question: Choose the right answer from options given a) five b) three c) zero d) seven
[A]:
b