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').

[Q]: 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
[A]: a


[Q]: Electrolytic capacitors have a finite lifetime, usually about ____ years.\Question: Choose the right answer from options given a) zero b) ten c) four d) eight
[A]: b


[Q]: Pets also track in pollen, and one out of every ____ people is allergic to cat or dog dander.\Question: Choose the right answer from options given a) no b) seven c) ten d) five
[A]:
c