X-Ray Bursters Are Objects in the Sky That Emit Sudden

X-ray bursters are objects in the sky that emit sudden bursts of X-rays in addition to a steady,low-level,X-ray emission.These bursts of X-rays are believed to be caused by

A) material transferred onto the surface of a neutron star in a binary system,then subsequently ignited in a thermonuclear explosion that leaves the neutron star intact to repeat the process.
B) material from a companion star pulled into an accretion disk around a black hole,with periodic clumps of material falling from the disk into the black hole to produce the X-rays.
C) material transferred onto the surface of a neutron star,causing the neutron star to collapse suddenly into a black hole.
D) material transferred onto the surface of a white dwarf in a binary star system,producing a thermonuclear explosion at the surface while leaving the white dwarf intact to repeat the process.