Question

A volcano is best defined as

Answer 1

a volcano is an opening in the crust of the earth through which molten rock material or magma comes out.

Step-by-step explanation:

Answer 2

a vent in the earth's crust through which lava, steam, ashes, etc., are expelled, either continuously or at irregular intervals.

Or

a mountain or hill, usually having a cup-like crater at the summit, formed around such a vent from the ash and lava expelled through it.