A mirror will reflect B. Some wavelengths of visible light that will shine on it. Every matter absorbs light in certain wavelength. The wavelength is absorbed by the molecules that make up the matter. The wavelengths of light that do not get absorbed are reflected back. As with mirror, it has a narrow absorption band for the wavelengths of light in visible spectrum (graph shows that silver mirror has 85% reflectance in the visible spectrum). Hence it appears to us that all of the visible light gets reflected.
