To establish the reliability and credibility of a secondary source, you must know which of the following?

a. information about the person who created the source, including his education, possible bias, or expertise b. information about the topic of the source, including its historical significance or possible applications it could have to the present day c. information about the history of the time period discussed, including what was going on or which important people were involved d. information about the source itself, including the number of copies it has sold or which countries recognize it as important