Answer:
Option-(B): The protolith is the un-metamorphosed rock.
Explanation:
Both are the same thing but the difference in the form, or we can say, that the prolith is the non-metamorphosed form and the slate is metamorphosed form of the same substance. As the slate is the fine grained form of rock and it posses very unique structure, as these rocks are mostly in the construction and designing purpose of beautification of buildings of various types.
