Questions: Choose the answer that best matches the description or term. A. ADH B. aldosterone C. ANP D. NO E. norepinephrine B locally acting; causes vasodilation

The answer is D: NO (Nitric Oxide).

Explanation for each option:

A. ADH (Antidiuretic Hormone): This hormone is involved in water retention by the kidneys and does not primarily cause vasodilation. It is not locally acting in the context of vasodilation.

B. Aldosterone: This hormone regulates sodium and potassium levels and affects blood pressure but does not cause vasodilation. It is not locally acting in terms of vasodilation.

C. ANP (Atrial Natriuretic Peptide): This hormone helps to reduce blood volume and pressure by promoting sodium excretion, but it is not primarily known for causing vasodilation in a local manner.

D. NO (Nitric Oxide): Nitric Oxide is a locally acting molecule that causes vasodilation by relaxing the smooth muscles in blood vessels. It is well-known for its role in regulating blood flow and pressure.

E. Norepinephrine: This neurotransmitter and hormone typically causes vasoconstriction, not vasodilation, and is not locally acting in the context of vasodilation.

In summary, Nitric Oxide (NO) is the correct answer as it is a locally acting molecule that causes vasodilation.