Answer:
a border surrounding the zone of strong gravity near a black hole.
Step-by-step explanation:
The event horizon is the place where the gravity begins to become so strong no light can escape the gravitational pull of the black hole. The event horizon is also known as "the point of no return" because it is impossible to escape the gravitational pull at that point. Light and matter begin to stretch and be pulled into the center and compressed into the matter that makes up the black hole.