Which of These Important Components Does a Planetary Nebula Contribute $\alpha$

Multiple Choice

Which of these important components does a planetary nebula contribute to the interstellar medium?

A) molecules such as NH₃ and CH₄, which contribute to giant molecular clouds
B) UV light photoionizes hydrogen. The hydrogen, on recombination, produces the red Balmer- $\alpha$ light by which interstellar emission nebulae are seen.
C) rotational motion from the original star, which serves to concentrate interstellar matter into new stars and planetary systems
D) nuclei of moderately heavy elements, major components of planets such as Earth.