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]: Collars come in ____ shapes.\Question: Choose the right answer from options given a) six b) two c) four d) zero
[EX A]: b

[EX Q]: Most children improve in three to ____ days.\Question: Choose the right answer from options given a) seven b) six c) four d) ten
[EX A]: a

[EX Q]: Eaglets develop feathers within the first month, and begin to fly at ____ months.\Question: Choose the right answer from options given a) three b) six c) zero d) ten
[EX A]:
a