Light of a Given Wavelength Is Used to Illuminate the Surface

Multiple Choice

Light of a given wavelength is used to illuminate the surface of a metal,however,no photoelectrons are emitted.In order to cause electrons to be ejected from the surface of this metal you should

A) use light of a longer wavelength.
B) use light of a shorter wavelength.
C) use light of the same wavelength but increase its intensity.
D) use light of the same wavelength but decrease its intensity.