The zone of earthquake activity along the upper portion of a sinking plate, as it scrapes past the opposing plate, in a subduction zone

• A. Benioff zone
• B. Bioaccumulation
• C. Biogas
• D. Biomagnification

Answer: (A)

The concept being tested is the pattern of earthquakes in a subduction zone. When one tectonic plate sinks beneath another, earthquakes occur along a dipping plane that follows the edge of the sinking slab. This seismic zone runs from near the trench down into the mantle and is tied to the subducting plate’s movement—it's known as the Wadati-Benioff zone (often shortened to Benioff zone). The name reflects that these earthquakes outline the interface and depth of the subducting slab as it scrapes past the overriding plate.

The other terms refer to environmental processes unrelated to earthquakes, so they don’t fit the description of seismic activity in subduction zones.