Detailed Instructions: In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.
Q: The radiation per unit solid angle of a wave undergoing this process varies with the cosine of the angle between the line of sight and the perpendicular. Lambert's emission law applies to the directionally independent form of this process, in which a microscopically rough interface causes it to occur in many different angles in the "diffuse" type of this phenomenon. The "specular" variety of this process is modeled by a law which states that the angle of incidence equals this process's namesake angle. For 10 points, name this optical phenomenon in which a wavefront rebounds off of a surface, often facilitated by mirrors.
A:
Science