Which Important Component Does a Planetary Nebula Contribute to the Interstellar

Which important component 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 that photoionizes hydrogen. The hydrogen, on recombination, produces the red Balmer α light by which we see interstellar emission nebulae.
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 our own