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: Heme is made of ____ pyrrole groups united to form a porphyrin ring.\Question: Choose the right answer from options given a) five b) four c) eight d) six

Output: b


Input: Consider Input: Double price is based on two golfers sharing ____ room.\Question: Choose the right answer from options given a) one b) zero c) six d) nine

Output: a


Input: Consider Input: Spiny mice are mature at the age of seven weeks and they are fully grown at ____ hundred fifty days.\Question: Choose the right answer from options given a) three b) one c) seven d) two


Output: b