In a subduction zone, some of the molten material—the former seafloor—can rise through which feature located near the trench?

• A. Mountain
• B. Fault
• C. Volcano
• D. Rift

Answer: (C)

In subduction zones, fluids released from the sinking oceanic plate lower the melting point of the overlying mantle, creating magma. This molten material then starts to move upward through the crust and mantle, feeding surface eruptions that form volcanoes along the overriding plate near the trench. So the path of rising magma reaches the surface as a volcano, creating the volcanic arc that sits parallel to the trench.

The other structures aren’t the primary avenue for magma to reach the surface in this setting. Mountains form mainly from crustal thickening and uplift, not direct magma ascent; faults are cracks that can host some movement or magma intrusion but aren’t the main volcanic pathway; rifts are zones of crustal spreading, not the subduction-related setting near a trench.