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').

Input: Consider Input: Potassium helps maintain fluid regulation and normal pH. All ____ help normalize.\Question: Choose the right answer from options given a) three b) six c) two d) one

Output: a


Input: Consider Input: Birds have ____ eyes.\Question: Choose the right answer from options given a) eight b) five c) nine d) two

Output: d


Input: Consider Input: China has more than ____ times as many people as the United States.\Question: Choose the right answer from options given a) four b) ten c) five d) one


Output: a