The Angular Resolution Attainable with a Radio Telescope, Compared to That

The angular resolution attainable with a radio telescope, compared to that attainable with an optical telescope of the same diameter, is significantly inferior because:

A) the wavelength of radio waves is larger than that of visible light.
B) it is difficult to make a reflector for radio waves since these waves penetrate most materials.
C) Earth's atmosphere disturbs radio waves from space much more than it does visible light.
D) radio wavelengths are smaller than visible wavelengths, making it difficult to produce a reflector sufficiently smooth to produce images.