Once a Black Hole Forms, the Size of Its Event

Multiple Choice

Once a black hole forms, the size of its event horizon is determined only by

A) the size (diameter) of the star that collapsed into the black hole
B) the mass inside the event horizon
C) the time since the black hole formed
D) the composition of the material that formed the black hole
E) you can't fool me; every black hole has an event horizon of the same size