In Astronomical Terms, Planetary Nebulae Are

Multiple Choice

In astronomical terms, planetary nebulae are

A) very long-lived objects, having been in existence since just after the Big Bang at the beginning of the universe.
B) relatively short-lived, existing around the central white dwarf star for millions of years before slowly spreading into space.
C) relatively long-lived since they form when the original stars form and remain as slowly rotating shells for the whole of their lifetimes of several billion years.
D) very short-lived, with lifetimes of about 20,000 years.