Recently, It Has Become Possible to Equip Telescope Mirrors with Mechanical

Recently, it has become possible to equip telescope mirrors with mechanical devices called actuators, which can move a portion of the mirror small distances very rapidly. Three of the statements below describe consequences of employing this technique, and one does not. Which statement is the exception?

A) active optics - the ability to change the shape of the mirror to compensate for sagging and for expansion/contraction as the mirror temperature changes
B) adaptive optics - the ability to change the shape of the mirror to compensate for atmospheric changes that would otherwise distort the image
C) the capability of creating segmented mirrors much larger than any single-piece mirror
D) the ability to build a single mirror that can detect electromagnetic radiation all across the spectrum, from gamma rays to radio waves