Select the reasons why most professional telescopes are reflectors rather than refractors. a) A lens has to be supported only around its edges.
b) Only the front surface of a mirror has to have a precise shape.
c) Reflecting telescopes have shorter focal lengths than refracting telescopes.
d) It is easier to make a large reflecting telescope than a large refracting telescope.
e) Lenses are not subject to chromatic aberration.
f) A reflector can collect more light than a refractor.