3. What is a subduction zone?

A subduction zone is the zone of earth crust where tectonic plates meet.

Explanation: A subduction zone is the zone of the Earth's crust where tectonic plates meet. Tectonic plates are massive pieces of the Earth's crust that interact with each other. The places where these plates meet are called plate boundaries. Plate boundaries occur where plates separate, slide alongside each other or collide into each other. Subduction zones happen where plates collide.

Result: Subduction zone is the zone of earth crust where tectonic plates meet.