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').

Background radiation comes from ____ sources.\Question: Choose the right answer from options given a) zero b) three c) four d) no
b

Widowed men are ____ times as likely to be murdered.\Question: Choose the right answer from options given a) two b) four c) three d) no
b

Babies are introduced to solid food about ____ months of age.\Question: Choose the right answer from options given a) eight b) five c) six d) ten

c