The work function of a photosensitive material is $4.0 \mathrm{eV}$. The longest wavelength of light that can cause photon emission from the substance is (approximately) (1) $310 \mathrm{~nm}$ (2) $3100 \mathrm{~nm}$ (3) $966 \mathrm{~nm}$ (4) $31 \mathrm{~nm}$