Respuesta :
A direct source of material for the formation of metamorphic rock is: D. existing rock.
What is a metamorphic rock?
A metamorphic rock can be defined as a type of rock which is typically formed as a result of the transformation of an existing rock, especially when it undergoes certain chemical and physical processes such as:
- High heat
- High pressure
- Hot mineral-rich fluids.
This ultimately implies that, an existing rock serves as a direct source of material for the formation of metamorphic rock.
Read more on metamorphic rock here: https://brainly.com/question/7669545
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