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 children have a vocabulary of eight to ____ words, including names, by eighteen months of age.\Question: Choose the right answer from options given a) ten b) one c) seven d) eight
[EX A]: a

[EX Q]: Elephants rise ____ inches when they inhale.\Question: Choose the right answer from options given a) two b) five c) one d) eight
[EX A]: a

[EX Q]: Microorganisms are an essential part of Form ____ biology.\Question: Choose the right answer from options given a) three b) six c) five d) ten
[EX A]:
c