Why are molecular lines more complex than elemental spectral ...

[plus1]

Why are molecular lines more complex than elemental spectral lines?
A) Molecules have two or more atoms.
B) Molecules can vibrate and rotate as well.
C) Molecules are heavier than atoms.
D) Molecules are the basis of life.
E) Most of the universe is made of molecules, not individual atoms.

[notis]

I know the answer! It's B.