Spherical Aberration Is a Description of the Fact That a Spherical

Multiple Choice

Spherical aberration is a description of the fact that a spherical mirror has a focal length (call it f_f) for light striking it far from the central axis that differs from the focal length (call it f_c) for light striking it close to the central axis. By taking the "limiting" case of a hemisphere it becomes clear that

A) f_f < f_c for the outer rays not "far" from as well as for outer rays farther from the central axis.
B) f_f < f_c for the outer rays not "far" from the central axis, and f_f > f_c for outer rays farther from the central axis.
C) f_f > f_c for the outer rays not "far" from the central axis, and f_f < f_c for outer rays farther from the central axis.
D) f_f > f_c for the outer rays not "far" from as well as for outer rays farther from the central axis.