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]: Reverse osmosis uses three to ____ gallons of water to produce one gallon of drinking water.\Question: Choose the right answer from options given a) six b) eight c) five d) ten
[EX A]: d

[EX Q]: Classes play ____ distinct roles in object-oriented programming.\Question: Choose the right answer from options given a) eight b) zero c) two d) no
[EX A]: c

[EX Q]: Polychrome is a decorative style, which utilizes at least ____ colors on the same piece of ceramic.\Question: Choose the right answer from options given a) two b) ten c) three d) zero
[EX A]:
c