Answer:
At heart, all life on Earth uses a membrane that separates the organism from its environment. ... In this regard, water is essential simply because it's a liquid at Earth-like temperatures. Because it flows, water provides an efficient way to transfer substances from a cell to the cell's environment.
Region A, Hope this helps.
Answer: Kidney
Explanation: The Kidneys produce the hormone in response to cellular hypoxia due to loss of blood.
I believe the answer is D) Eukarya