Answer:
D. is a hard stone that is easily available everywhere.
Step-by-step explanation:
Slate is a type of a rock. It is found in its natural form in the nature. It is a fine grain homogeneous metamorphic rock. It is hundred percent natural rock and is a mineral product. Slate is an expensive product.
Many people used slate roofing in their houses because slate is one of the most sustainable material and durable material. It is a hard rock that is available on every parts of the world such as India, China, Germany, Brazil, Venezuela, Wales, England, Mexico and many more.