What Do the Textbook Authors Suggest About Using the Website

What do the textbook authors suggest about using the website Ratemyprofessors.com to get information about a professor?

A) Its ratings provide an objective and valid source of information.
B) Though limited, it is as useful as any other source of information.
C) It is an untrustworthy source of information.
D) Its reliability depends on whether a professor is rated by a large enough sample of students.