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: National forests have regulations that restrict ____ wheeler use to established roads.\Question: Choose the right answer from options given a) no b) four c) six d) nine

Output: b


Input: Consider Input: Centrifugal pumps can usually handle up to about ____ percent by volume of air.\Question: Choose the right answer from options given a) one b) five c) eight d) seven

Output: b


Input: Consider Input: Photons have ____ mass or charge, but are electromagnetic, as are light, uv, and radio waves.\Question: Choose the right answer from options given a) eight b) three c) no d) zero


Output: c