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').

Neutrinos are particles with almost ____ mass and no electric charge.\Question: Choose the right answer from options given a) no b) two c) zero d) five
a

Some infected horses show ____ signs and become chronic carriers of the disease.\Question: Choose the right answer from options given a) nine b) six c) four d) no
d

Democracy is more than casting a ballot every ____ years.\Question: Choose the right answer from options given a) zero b) four c) two d) six

b