A smooth, polished surface.
-Reflection is the bouncing back of light when it hits a surface or a boundary. Therefore, when light rays are hits or are incident on a smooth, flat surface, they bounce or reflect away from the surface at the same angle as they arrive.
-Thus, from the law of reflection the angle of incident will be equal to the angle of reflection.
-The best surfaces for reflecting light are very smooth, such as a glass mirror or polished metal surfaces.