A Reflecting Telescope Has the Advantage That Its Main Optic

A reflecting telescope has the advantage that its main optic has only one element (a curved mirror) and that this element does not have to be made of transparent material. In contrast, the simplest high-quality refracting telescope needs two elements in its main optic (a converging lens) and both elements must be perfectly transparent. It needs these two transparent elements in its lens because a single element lens

A) can only form a virtual image and not a real image.
B) causes light to spread apart rather than come together.
C) will produce an inverted real image while a two element lens will produce an upright real image.
D) cannot bring all the colors to a focus at the same distance.