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: Photosynthesis occurs in ____ phases.\Question: Choose the right answer from options given a) four b) two c) nine d) five
Example Output: b

Example Input: Basting is the stitching used to hold the ____ layers of fabric together while quilting.\Question: Choose the right answer from options given a) four b) six c) three d) ten
Example Output: c

Example Input: Modern guitars come in ____ main types.\Question: Choose the right answer from options given a) two b) ten c) seven d) four
Example Output:
d