No photoelectrons are emitted from a metal if the wavelength of light exceeds 6000 A. The work function of the metal is approximately equal to

A. 3 × 10⁻¹⁶ J
B. 3 × 10⁻¹⁹ J
C. 3 × 10⁻²⁰ J
D. 3 × 10⁻²² J