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: Chemistry has ____ less important names.\Question: Choose the right answer from options given a) ten b) no c) eight d) nine
Example Output: b

Example Input: Whales are divided into ____ categories, based on their teeth.\Question: Choose the right answer from options given a) two b) four c) nine d) ten
Example Output: a

Example Input: Some studies show that cloth diapering has ____ times the burden on water supplies than disposables.\Question: Choose the right answer from options given a) six b) one c) no d) four
Example Output:
d