Why is the parent rock a unique identifier for metamorphic rock types, but is not used to identify sedimentary or igneous rocks? state your answer in 1-2 sentences.

That is because metamorphic rock is formed by parent rocks that are either sedimentary rock or igneous rocks and we can use the former rock type to distinguish the type of metamorphic rock, marble was igneous rock exposed to high pressure or temperature.

While the other two type of rocks are formed initially by sedimentation and volcanic movements and has no parent rocks.

Yes, as metamorphic rocks are formed by the weather and conversion of the sedimentary rocks.

Explanation:

separation of church and state? not sure what you mean.