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]: Songbirds have ____ sets of vocal chords.\Question: Choose the right answer from options given a) six b) two c) eight d) ten
[EX A]: b

[EX Q]: Babies show an interest in solid foods when they are approximately four to ____ weeks old.\Question: Choose the right answer from options given a) nine b) eight c) five d) six
[EX A]: c

[EX Q]: Cubs stay with their mothers from one and a half to ____ years.\Question: Choose the right answer from options given a) three b) zero c) no d) six
[EX A]:
a