What object has gravity so strong that nothing, not even light, can escape it?

A black hole is an astronomical object with a gravitational pull so intense that escape velocity exceeds the speed of light. This phenomenon occurs when a massive star collapses under its own gravity after exhausting its nuclear fuel, compressing its matter into an incredibly small volume. As a result, the gravitational field at the black hole's event horizon—the boundary beyond which nothing can escape—becomes impenetrable to all forms of matter and energy, including light.

This unique characteristic is due to the extreme warping of space-time that occurs around a black hole, making it a fascinating subject in both astrophysics and general relativity. In contrast, other options like neutron stars and red giants do not have such intense gravitational fields that trap light. Neutron stars are incredibly dense but are not quite at the threshold of becoming a black hole, while red giants are at a different stage of stellar evolution where they expand rather than collapse into a singularity. Quasars, on the other hand, are incredibly luminous objects powered by supermassive black holes, but they themselves are not the black holes. Thus, the strongest gravitational pull associated with the inability of light to escape pertains specifically to black holes.