Compton Scattering Practice Test

In Compton scattering, an incident photon of wavelength $\lambda$ scatters from an electron and emerges with wavelength $\lambda'>\lambda$. Which conclusion about light is supported by observing $\lambda'>\lambda$?

In Compton scattering, $\lambda$ increases after a photon scatters from an electron. A student claims the change is due to the photon giving some of its momentum to the electron. Which statement is consistent with this claim and the measured wavelength increase?