Your Best Friend Passes You in the School Hallway and Glares

Your best friend passes you in the school hallway and glares at you without speaking. You think, "Now, why did she do that?" One possible explanation could be that she saw you flirting with her boyfriend. Within the framework of the scientific method, this possible explanation about your friend's behavior will remain tentative until it is objectively verified by asking your friend why she did not speak to you. Thus, this testable hunch would be considered a(n)

A) theory.
B) operational definition.
C) hypothesis.
D) relative certainty.