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: Selenium is ____ times more poisonous than arsenic.\Question: Choose the right answer from options given a) one b) five c) eight d) two

Output: b

Input: Consider Input: Pandas reach adulthood at about ____ years of age.\Question: Choose the right answer from options given a) eight b) seven c) five d) six

Output: c

Input: Consider Input: Friction occurs when ____ substances rub together.\Question: Choose the right answer from options given a) no b) three c) two d) nine
Output: c