Task: Class Definition Understanding (ontology: Earth_Environment/SWEET)

Which of the following definitions best describes 'volcanic rock'?

A. A massive pillar of rock more resistant to erosion than the lavas and pyroclastic rocks of a volcanic cone.
B. the concept is an igneous rock produced by extrusion from a volcano. It has various subtypes based on chemical composition and whether the extrusion was violent (pyroclastic) or slow (laval). [Wikipedia]
C. The mantle is composed mostly of Ultramafic rocks (or see Igneous Primer) such as peridotite and dunite and their metamorphic equivalents (e.g. ecologite). [Wikipedia]
D. Volcanic rock (or lava) that characteristically is light in color and contains 62% to 69% silica and moderate a mounts of sodium and potassium.

Answer: the concept is an igneous rock produced by extrusion from a volcano. It has various subtypes based on chemical composition and whether the extrusion was violent (pyroclastic) or slow (laval). [Wikipedia]