Final answer:
Depositional landforms like beaches, spits, coastal dunes, and barrier beaches are formed through sedimentation and different physical processes.
Step-by-step explanation:
Depositional landforms are formed by the accumulation and deposition of sediments in various environments. Beaches are not formed as a result of volcanic eruptions, but rather from the deposition of sand and other sediments by wave actions along the coastline (D). Spits, which are narrow strips of land extending into a body of water, are formed due to the movement of sediment, often driven by tides, currents, or longshore drift, not tectonic plate movements (B). Coastal dunes are shaped by the action of wind carrying and depositing sand particles, not glaciers (C). Barrier beaches, which are long, narrow landforms separated from the mainland by a lagoon or marsh, are primarily formed by the accumulation of sediment carried by waves and currents (D).