b
A green leaf reflects green light and so it appears to be green. It absorbs other wavelengths of incident light. When incident light has no wavelength corresponding to green, the leaf will reflect no colour and appear black. This happens when incident light is laser light of wavelength 0.6328 \(\mu \mathrm{m}\). Wavelength of green colour is much less than \(0.6328 \mu m\)

The leaf absorbs the incident laser light, reflects no colour and appears black.