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]: Heme is made of ____ pyrrole groups united to form a porphyrin ring.\Question: Choose the right answer from options given a) five b) four c) eight d) six
[EX A]: b

[EX Q]: Nightmares happen frequently in childhood, especially between the ages of ____ and six.\Question: Choose the right answer from options given a) three b) eight c) no d) ten
[EX A]: a

[EX Q]: Hurricane season begins in ____ weeks.\Question: Choose the right answer from options given a) five b) no c) two d) three
[EX A]:
c