Select the volcanoes that are generally formed from only one type of igneous material (for example, pyroclastic material).

a. cinder cone

b. stratovolcano

c. shield volcano

The correct answer should be Cinder Cone, that is A.

They are often made out of pyroclastic material. Stratovolcanos are made out of various materials, while shield volcanoes also often mix with elements such as water and other layers of basalt created from previous eruptions.