What Are X-Ray Bursters

What are X-ray bursters?

A) They are the central sources of energy for planetary nebulae.
B) They are very massive stars that explode as supernovae, emitting bursts of X-rays and gammarays in the process.
C) They are rapidly rotating black holes whose precession points their poles toward us onoccasion.
D) They are violent energy sources known to lie at the heart of the Milky Way and similarmassive galaxies.
E) They are neutron stars on which accreted matter builds up, then explodes in a violent nuclearexplosion.