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: Microwave ovens emit ____ kinds of radiation.\Question: Choose the right answer from options given a) six b) two c) four d) eight
Example Output: b

Example Input: Hybridization is the practice of ____ different species interbreeding.\Question: Choose the right answer from options given a) no b) one c) two d) three
Example Output: c

Example Input: Bacteria acquire genes conferring resistance in any of ____ ways.\Question: Choose the right answer from options given a) zero b) no c) three d) five
Example Output:
c