An author’s qualifications are important in determining whether a media source is... credible.
relevant.
valid.
copyrighted.

An author's qualifications are important in determining whether a media source is;

Credible

Explanation:

In order to find out about the credibility of an author, the preface, forward, and or introduction including the book's back cover should be checked for the author's credentials, qualifications and areas where the author is an expert

The author's credential can also be checked by finding out about other books the author has written and also about the author's biography.