Concept:Metamorphic rocks form when existing rocks are transformed by heat, pressure, or chemical fluids.
Explanation:Slate is derived from fine-grained sedimentary rocks (like shale) that are metamorphosed.
Marble is formed from limestone (a sedimentary rock) that is recrystallized under heat and pressure.
Both slate and marble show compact texture, high strength, and low water permeability.
They are not primary, igneous, or sedimentary rocks.
Thus, they belong to the metamorphic rock group.
Answer:D. Metamorphic rocks