The function of a lens is to change the

Question

A. refraction of light rays or waves.
B. absorption of light rays or waves.
C. frequencies of light in various directions.
D. direction of light rays or waves.

Answer 1

If you have a textbook or can find online a picture of something called a ray diagram for a lens, take a look at it and see how light rays change as they go through.  I think it matches one of the answers above better than the others.