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]: Gases are perhaps the best understood of the ____ states of matter.\Question: Choose the right answer from options given a) three b) five c) nine d) zero
[EX A]: a

[EX Q]: Female cats can go into heat for the first time as early as ____ months of age.\Question: Choose the right answer from options given a) four b) zero c) five d) eight
[EX A]: c

[EX Q]: Motive power is of ____ kinds.\Question: Choose the right answer from options given a) six b) two c) three d) ten
[EX A]:
b