What happens in a subduction zone? a. Two plates slide past each other and cause earthquakes.
b. Two plates come together of different densities and one sinks under the other and melts.
c. Two oceanic plates diverge and create a ridge.
d. Two continental plates collide and form mountains.

b. Two plates come together of different densities and one sinks under the other and melts.

Explanation:

Subduction zones are places in the lithospheric plate where the convergent boundary happens. Two plates come together, and one thrusts another and pushes it underneath. The first plate goes above the second one, which sinks in the ground.

The plate which has sunk under will end up partly melting by the magma inside of the earth. This eventually can lead up to the creation of the eruption of the vulcanos.

This is why the volcanos and earthquakes form at the subduction zones.

Eath is made up out of these tectonic plates, and the zones in which they meet have more frequent earthquakes.