The answer is D because they speard apart or interact in all boundaries.
Answer:
In simplest terms, water makes up about 71% of the Earth's surface, while the other 29% consists of continents and islands.
Explanation:
Second messenger systems: The amino acid-derived hormones epinephrine and norepinephrine bind to beta-adrenergic receptors on the plasma membrane of cells. Hormone binding to receptor activates a G protein, which in turn activates adenylyl cyclase, converting ATP to cAMP.
