A planetary nebula can have distinct colours because Select one alternative:
O A. Planets have a complex surface.
O B.Different parts of the nebula have different blackbody temperatures.
O C. It is an emission nebula, and most of its light is associated with distinct spectral lines.
O D. Their light is distorted by the Earth's atmosphere; the different colours are an optical illusion.
O E. They actually contain many stars, with different colours.
