Concept:A sill is a landform created by magma intrusion, making it igneous in origin.Explanation:A sill forms when magma is pushed between horizontal layers of rock and then cools into a sheet-like mass.This makes it a direct product of volcanic activity.Zeugen are formed by wind erosion.Loess is made by wind deposition.A gorge is created by river erosion.Therefore, the only feature of volcanic origin is the sill.Answer:A. Sill