Abeam of light traveling in air strikes a glass slab at an angle of incidence less than 90°. after entering the glass slab, what does the beam of light do? (there could be more than one correct choice.)

It gets refracted.

Explanation:

When light beam travels through different mediums they refract i.e. they change their direction.  Here the angle of incidence is less than 90°. After entering the glass slab the light beam will move towards the normal (a line drawn perpendicular to the interface of the two mediums). Thus the  angle of refraction will be even lesser than angle of incidence.