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').
--------
Question: Cats have ____ sets of vocal cords.\Question: Choose the right answer from options given a) zero b) nine c) two d) three

Answer: c


Question: Baby elephants are usually dependent on mother s milk for at least ____ years.\Question: Choose the right answer from options given a) six b) three c) two d) seven

Answer: b


Question: Economic systems are in reality ____ sector open economies.\Question: Choose the right answer from options given a) one b) seven c) nine d) three

Answer:
d