Question

Rays of light incident on a lens and parallel to the principal axis of the lens converge

A. at the focal point of the lens.
B. at the center of curvature of the lens.
C. in front of the lens.
D. in back of the lens.

Answer 1

focal    point of the lens

Answer 2

D. in back of the lens, because the rays are unaffected until it goes through the lens. In that moment the direction of the rays is modified, making them get closer to each other and all of them converge in a point behind the lens.