Mirrors and lenses can be used in telescopes - Edexcel - GCSE Physics - Question 3 - 2012 - Paper 1

When a ray of light strikes a plane mirror, it reflects off the mirror at an angle equal to the angle of incidence. This is in accordance with the law of reflection, which states that the angle of incidence is equal to the angle of reflection. Therefore, the correct diagram that illustrates this behavior is Diagram B, where the incoming ray and the outgoing ray are symmetrical around the normal line.