How do you determine whether or not your sources are credible when you are researching and writing for school or work?

Select 4 statements which could be considered a "theme" of a story, play, poem, etc. a. sometimes the most profound ideas can come from unfamiliar places. b. my best friend jeffrey has many unusual interests. c. once a man gives his soul over to evil, he can never go back. d the three sheepdogs lay around the yard all day. e a priest's collar has an unusual effect upon people. f innocence is a powerful force in a world full of corruption. g king lear is a play shakespeare wrote later. evil often wears the disguise of innocence.