Final answer:
The escape velocity for material inside a black hole is greater than the speed of light. When the escape velocity equals or exceeds the speed of light, nothing, not even light, can escape the black hole's gravitational pull.
Step-by-step explanation:
The escape velocity for material inside a black hole is greater than the speed of light. When the escape velocity equals or exceeds the speed of light, nothing, not even light, can escape the black hole's gravitational pull. This is because the black hole's immense gravity bends spacetime to such an extent that anything within its event horizon is trapped indefinitely.