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]: Natural indium contains ____ isotopes.\Question: Choose the right answer from options given a) one b) eight c) two d) seven
[A]: c


[Q]: Most internal parasites are specific to one or ____ species.\Question: Choose the right answer from options given a) seven b) three c) two d) five
[A]: c


[Q]: Structural unemployment is high with about one in ____ persons officially unemployed.\Question: Choose the right answer from options given a) two b) ten c) three d) no
[A]:
c