Atomic Structure: JEE Main 2019 Chemistry question

What is the work function of the metal if the light of wavelength 4000$\mathop A\limits^ \circ$ generates photoelectrons of velocity 6 $\times$ 10⁵ ms^–1 from it ? (Mass of electron = 9 $\times$ 10^–31 kg; Velocity of light = 3 $\times$ 10⁸ ms^$-$1 Plank's constant = 6.626 $\times$ 10^–34 Js; Charge of electron = 1.6 $\times$10^–19 JeV^–1)