In Each Situation, Indicate Whether the Method of Data Collection

In each situation, indicate whether the method of data collection is biased.
-A campus bookstore is holding a drawing to give away five free textbooks (one per student) . Students enter the contest by writing their name and contact information on an index card. The index cards were placed in a bowl, thoroughly mixed around, and five cards were selected. Those five students were contacted and received their free textbook.

A) Not biased
B) Biased