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. in back of the lens.
c. in front of the lens.
d. at the center of curvature of the lens.

A. at the focal point of the lens.

Explanation:

The lens is a device of a certain type of curvature that bends light causing optical phenomena. The focal point of a lens or focus is the point where rays converges in a convex lens or diverges from in a concave lens.

The convex lens concentrates the rays to a point, whereas in a concave lens the rays diverge from a point. The point on the principal axis is called focal point or focus.

Hence, the answer is A. at the focal point of the lens.