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 Input:
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 Output:
d


Ex Input:
Right whales are slow swimmers, averaging just ____ miles per hour.\Question: Choose the right answer from options given a) nine b) six c) two d) five

Ex Output:
b


Ex Input:
Moderation is defined by at least one beer company as drinking up to ____ drinks a day.\Question: Choose the right answer from options given a) three b) four c) ten d) two

Ex Output:

b