Answer: Then, due to various conditions within the Earth, the existing rock was changed into a new kind of metamorphic rock. The conditions required to form a metamorphic rock are very specific. The existing rock must be exposed to high heat, high pressure, or to a hot, mineral-rich fluid.
Explanation:
A placebo experiment is one that does no harm or good. A lot of the time researchers will have a. placebo group and a another control group with the actual treatment. The key in placebo is that no one knows if they have it or not. C
Answer:
i believe its alveoli
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Explanation: