In Astronomical Terms,planetary Nebulae

Multiple Choice

In astronomical terms,planetary nebulae

A) exist around their central white dwarf stars for millions of years before slowly spreading into space.
B) are relatively long-lived because they form when the original stars form and remain as slowly rotating shells for the whole of the star's lifetime of several billion years.
C) are very short-lived,with lifetimes of about 50,000 years.
D) are very long-lived objects,having been in existence since the Big Bang at the beginning of the universe.