Stopping potential depends on frequency of incident light and nature of the emitter material. It is independent of the power of the light source.
Maximum kinetic energy of photoelectrons is stated asKEmax=hν−ϕ=λhc−ϕ, Where, h is the Planck’s constant, ν is the frequency, λ is wavelength of incident light and ϕ is the work function of the metal surface.
Thus, the maximum kinetic energy of the photoelectron depends on the wavelength of the incident light.
So both statements I and II are correct