Which volcano type has a small, steep-sided structure with one vent at the surface?

• A. Cinder Cone Volcano
• B. Composite Volcano
• C. Caldera
• D. Epicenter

Answer: (A)

Think about how a volcano’s shape reflects how it erupts. A cinder cone forms when eruption ejecta—ash, cinders, and volcanic bombs—falls around a single vent, piling up into a small, steep-sided cone with a crater at the top. The material is loose and chunky, so the cone is steep, relatively short, and strongly centered on one surface vent. That exact combination—small size, steep sides, and one vent—is what this description points to.

In contrast, a composite or stratovolcano is a tall, broad mountain built from many layered lava flows and ash, usually with multiple vents and a longer eruptive history. A caldera is a huge depression created when a magma chamber empties and the summit collapses, far larger than a simple cone. An epicenter isn’t a volcano feature at all; it’s a point on the Earth's surface where an earthquake is felt.

So the description matches a cinder cone volcano.