Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: The largest-mass stars become black holes . These extremely large stars end their life in the same way as a medium-mass star in that they become a supernova. After the outer layers are blown away in the supernova, however, the core of the star shrinks down in volume but still has a huge mass. The density of this object is extremely high, even denser than neutron stars. This dense object will have a gravitational force so large that not even light can escape from the body. (A companion topic to this occurs in The General Theory of Relativity where we see than extremely strong gravitational attraction can even attract light. ) These objects appear black because light cannot leave them, that is, they pull all light back to their surface. Black holes capture everything nearby due to their massive gravity and so they grow in size. Black holes are a common topic for science fiction but keep in mind, they are simply a very dense ball of matter with intense gravitational attraction. Answer: black holes
A: 
Very large stars eventually become what extremely dense space regions, which are so dense that no light can escape from them?