A light .ray is incident to a plane mirror at an angle of ${20}^o$.What would be the angle between the incident ray and the reflected ray?

The correct option is B ${40}^o$
We know law of reflection that the angle of incidence is equal to angle of reflection, also the incident ray, reflected ray and normal are on same plane.

So angle of reflection is ${20}^o$.

So the angle between incidence and reflected ray is ${40}^o$