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]: Chlorine has ____ naturally occurring isotopes.\Question: Choose the right answer from options given a) nine b) eight c) three d) two
[EX A]: d

[EX Q]: Reptiles also have scaly skin and a ____ chambered heart.\Question: Choose the right answer from options given a) zero b) one c) ten d) three
[EX A]: d

[EX Q]: Wrens often have ____ broods per season.\Question: Choose the right answer from options given a) two b) five c) eight d) one
[EX A]:
a