The Gas in a Planetary Nebula Is Composed of

Multiple Choice

The gas in a planetary nebula is composed of

A) primarily hydrogen from the surrounding interstellar medium.
B) primarily hydrogen from the post-asymptotic giant branch star.
C) hydrogen and heavier elements like helium and carbon processed in the core of the post-asymptotic giant branch star.
D) primarily helium from the post-asymptotic giant branch star.
E) carbon and helium from the nuclear reactions that took place on the horizontal branch.