Final answer:
Quartzite is the correct example of a metamorphic rock. It forms from the alteration of quartzose sandstones or siltstones and is known for its hardness and resistance to acid.
Step-by-step explanation:
The example of metamorphic rock provided in the options is C. Quartzite. Quartzite is a common, crystalline-textured, intermediate- to high-grade metamorphic rock that forms from the metamorphism of quartzose sandstones or siltstones. It is characterized by its hard nature (hardness = 7 on the Mohs scale), its resistance to reacting with acid (which distinguishes it from marble), and its variable color.
The process of forming metamorphic rocks involves the alteration of existing rocks—be they igneous or sedimentary—through high temperatures, high pressures, or chemical processes. As such, basalt and granite, being igneous, and limestone, being sedimentary, are not metamorphic. Therefore, among the options given, quartzite is the correct answer as it fits the definition of a metamorphic rock.