Concept:Igneous, sedimentary, and metamorphic rocks are classified mainly by their origin and physical appearance.Explanation:• Igneous rocks form from cooling magma or lava.• Sedimentary rocks form from compaction and cementation of sediments.• Metamorphic rocks form from existing rocks changed by heat and pressure.• These three major divisions are based on origin (how the rocks formed) and appearance.Answer:B. origin and appearance