(A) There is no time lag between the striking of light and ejection of electrons from the metal surface. The statement is correct as the electron gets immediately ejected as soon as the light of appropriate frequency strikes the metal surface. (B) The number of electrons ejected is independent of the intensity of light is incorrect. The number of electrons ejected depends on the intensity of incident radiation. (C) The elements K,Rb and Cs can show photoelectric effect when exposed to the beam of light is correct. Photoelectric effect can be normally observed in alkali metals as these have - low incident energy value/work function. ∴ (A) and (C) both are correct.