9．Which are the following statements correct?

(A)The maximum kinetic energy of the recoil electron in Compton scattering is given by ,where f is the frequency of the incident photon, h the Plank constant, c speed of the light and m rest mass of an electron.

(B)The black body radiation curve for different temperatures peaks at a wavelength inversely proportional to the temperature.

(C)The photon is massless so that the gravitational force will not affect its frequency as it leaves a star.

(D)The maximum kinetic energy of the emitted photoelectron depends on the frequency of the incident light.

(E)x-rays were found to be unaffected by electric and magnetic fields, to pass readily through opaque materials and to cause phosphorescent to glow.