Radio Waves Are Diffracted by Large Objects Such as Buildings

Radio waves are diffracted by large objects such as buildings, whereas light is not noticeably diffracted. Why is this?

A) Radio waves are unpolarized, whereas light is normally polarized.
B) The wavelength of light is much greater than the wavelength of radio waves.
C) Radio waves are polarized, whereas light is usually unpolarized.
D) The wavelength of light is much smaller than the wavelength of radio waves.
E) Radio waves are coherent and light is usually not coherent.