TASK DEFINITION: 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').
PROBLEM: 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

SOLUTION: d

PROBLEM: Metabolism have ____ stages-catabolism and anabolism.\Question: Choose the right answer from options given a) nine b) two c) five d) three

SOLUTION: b

PROBLEM: Water is the only substance on earth that exists naturally in ____ states.\Question: Choose the right answer from options given a) no b) three c) one d) two

SOLUTION:
b