Read the excerpt from A Black Hole is NOT a Hole.
According to context clues, which is the best definition of
event horizon?
Remember that super-pulling space around a black hole
the one with the strongest pull in the universe? That super
pull is the close-up gravitational power of a black hole. Here
in this zone, the gravity is so intense that nothing can move
fast enough to fly, launch, jump, or zoom away.
Around this extreme zone is a boundary called the event
horizon. This boundary acts like a point of no return. Once
past it, there's no going back. Only black holes have such
extreme gravity zones, and only black holes have event
horizons. This is what makes a black hole different from
everything else.
an area with not many events occurring near the horizon
an area with many events occurring near the horizon
a border surrounding very weak gravity found around a
black hole
a border surrounding the zone of strong gravity near a
black hole