Why Is There a Limit to How Much Compression Can

Why is there a limit to how much compression can be counterbalanced by electron degeneracy pressure?

A) At extreme compression,the electron speeds approach the speed of light and therefore cannot increase further.
B) At extreme compression,electrons are forced to stop moving,and once stopped there is nothing more they can do.
C) At extreme compression,atoms are fully ionized,so electrons go free and can no longer exert pressure.
D) The exclusion principle excludes electrons from exerting more pressure than the uncertainty principle would otherwise allow.
E) Electrons are very small and are simply incapable of exerting much pressure.