How an an HII region be told apart from a star with a spectroscope?

Question

How an an HII region be told apart from a star with a spectroscope?

Answer 1

Stars are black-body emitters; their spectrum is therefore continuous (not just lines).

An H-II region's light is due in large part to singly-ionized hydrogen.  That spectrum should therefore have a strong line at the appropriate wavelength.

This difference should be evident with a spectroscope, naturally.