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').

[EX Q]: Most infected persons have ____ symptoms of disease.\Question: Choose the right answer from options given a) six b) no c) three d) one
[EX A]: b

[EX Q]: Neutrinos are particles with almost ____ mass and no electric charge.\Question: Choose the right answer from options given a) no b) two c) zero d) five
[EX A]: a

[EX Q]: Ternary diagrams show the relative proportions of ____ variables on three axes.\Question: Choose the right answer from options given a) two b) one c) three d) eight
[EX A]:
c