Which of the following is true regarding the kinds of events we uncover looking at the Milky Way using different wavelengths of light?
a) Infrared reveals areas around star formation.
b) Radio waves reveal star-forming regions and the emission from CO from cold dark molecular clouds.
c) The 21-cm line reveals atomic hydrogen.
d) X-rays reveal locations of supernovae and hot bubbles of expanding gas.
e) All the above is correct.