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').

Input: Consider Input: Circles mark the approximate locations of ____ recently discovered solar systems.\Question: Choose the right answer from options given a) four b) no c) zero d) nine

Output: a


Input: Consider Input: Respiratory therapists complete ____ to four years of education.\Question: Choose the right answer from options given a) one b) nine c) zero d) two

Output: d


Input: Consider Input: Oxygen starvation leads to brain cells committing suicide over the following three to ____ days.\Question: Choose the right answer from options given a) four b) five c) nine d) two


Output: a