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: Ascidian tunicates come in ____ main forms.\Question: Choose the right answer from options given a) three b) zero c) four d) eight
Example Output: a

Example Input: Most aphthous ulcers heal in one to ____ weeks.\Question: Choose the right answer from options given a) two b) eight c) one d) seven
Example Output: a

Example Input: Particles can be on ____ places at the same time.\Question: Choose the right answer from options given a) seven b) nine c) two d) no
Example Output:
c