**Core Concept**
The sympathetic nervous system (SNS) is a division of the autonomic nervous system that activates the body's 'fight or flight' response. This is achieved through the release of neurotransmitters, such as norepinephrine, from sympathetic nerve endings onto various effector organs, including blood vessels.

**Why the Correct Answer is Right**
When the SNS is activated, it releases norepinephrine from the axons of sympathetic neurons onto the arteriolar wall. This leads to the activation of alpha-1 adrenergic receptors, which causes vasoconstriction (narrowing of the blood vessels). This response is crucial for increasing blood pressure and redirecting blood flow to muscles during times of stress or physical activity. The release of norepinephrine from sympathetic nerve endings is mediated by the enzyme tyrosine hydroxylase, which converts the amino acid tyrosine into L-DOPA, the precursor to norepinephrine.

**Why Each Wrong Option is Incorrect**
**Option A:** Norepinephrine is released by the vascular smooth muscle cells in response to alpha-1 adrenergic receptor stimulation, not by the vascular smooth muscle cells themselves. This is a classic exam trap, as the question seems to imply the release of norepinephrine by the target organ, rather than the neurotransmitter released by the sympathetic nerve.

**Option B:** Acetylcholine is the primary neurotransmitter released by the parasympathetic nervous system (PNS), which has the opposite effect of the SNS. The PNS promotes 'rest and digest' activities, such as vasodilation (widening of the blood vessels).

**Option D:** Nitric oxide (NO) is actually a vasodilator, produced by the endothelium (the inner lining of blood vessels). It stimulates the enzyme guanylyl cyclase, leading to the relaxation of vascular smooth muscle cells. Suppression of NO production would lead to vasoconstriction, not vasodilation.

**Clinical Pearl / High-Yield Fact**
When treating hypertension, it's essential to understand the role of the SNS in regulating blood pressure. Beta-blockers, which are commonly used to treat hypertension, work by blocking the effects of norepinephrine on beta-1 adrenergic receptors in the heart, leading to decreased cardiac output and blood pressure.

**✓ Correct Answer: C. Norepinephrine is released from axons onto the arteriolar wall**