What type of bomb does not require any action to trigger it?

A time bomb is a type of explosive device designed to detonate after a predetermined period or at a specific time. It operates by using a timer that counts down to the moment of detonation, which means that no external action is necessary for it to trigger. This characteristic distinguishes time bombs from other bomb types, as they are set to explode automatically based on their internal timing mechanism.

In contrast, action bombs, impact bombs, and remote-detonated bombs require some form of interaction or external stimulus to activate. Action bombs might be triggered by movement or pressure, impact bombs detonate upon being hit or subjected to a sudden force, and remote-detonated bombs rely on a triggering signal from a distance. Hence, the defining feature of a time bomb is its automated detonation, making it uniquely classified among these options.