**Correct option : (2) 1 volt**

**Explanation : **

The equation of a harmonic wave is given by E = E_{0} sin 2π/λ(vt - x)

The electric field associated with incident light is given by E_{0} sin 1.57 x 10^{7} ms^{-1}(ct - x) has the same form as of a harmonic wave.