Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor in order to signal a target cell to change its behavior. These are examples of hydrophilic hormones in animals: A. tyrosine-derived epinephrin and norepinephrin B. insulin and glucagon C. serotonin and melatonin (tryptophan-derived mammalian neurotransmitters D. All of the above E. None of the above

The correct answer is - D. all of the above.

Explanation:

Hydrophilic hormones are the hormones that can not pass through the cell membrane as they are poorly lipid-soluble and cannot pass through cell membranes and bind the receptors present on the surface of the membrane.  

Insulin and glucagon are peptide hormones that bind to a receptor in the target cell's membrane surface. Norepinephrine and epinephrine are catecholamines that are hydrophilic in nature.  Seratonin and Melatonin are also bound on the surface receptor due to their hydrophilic nature.

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation:

one centimetre is equal to 0.01 metres