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').

Example Input: Moles breed in late winter or spring and have a gestation period of ____ to six weeks.\Question: Choose the right answer from options given a) nine b) four c) six d) five
Example Output: b

Example Input: Turkey also has ____ inland drainage basins.\Question: Choose the right answer from options given a) zero b) two c) eight d) nine
Example Output: b

Example Input: Physicists now think of light in terms of photons, particles that have ____ mass but carry momentum.\Question: Choose the right answer from options given a) three b) eight c) four d) no
Example Output:
d