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').

Astronomers fall in ____ classes - professionals and amateurs.\Question: Choose the right answer from options given a) two b) four c) six d) zero
a

Classes play ____ distinct roles in object-oriented programming.\Question: Choose the right answer from options given a) eight b) zero c) two d) no
c

Tigers have sharp night vision which is ____ times greater than that of humans.\Question: Choose the right answer from options given a) six b) ten c) two d) seven

a