**Core Concept**
The autonomic nervous system regulates blood pressure through the sympathetic and parasympathetic divisions. The sympathetic nervous system increases heart rate, cardiac contractility, and vascular resistance, leading to an increase in blood pressure.

**Why the Correct Answer is Right**
The sympathetic nervous system achieves this increase in blood pressure through the release of neurotransmitters such as norepinephrine, which binds to adrenergic receptors on the heart and blood vessels. This binding causes an increase in heart rate and cardiac output, as well as vasoconstriction of the blood vessels, leading to an increase in peripheral resistance and blood pressure.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided, so we cannot evaluate it.
**Option B:** Incorrect because the parasympathetic nervous system decreases heart rate and cardiac output, leading to a decrease in blood pressure.
**Option C:** Incorrect because the renin-angiotensin-aldosterone system (RAAS) increases blood pressure by increasing peripheral resistance, but it is not directly related to the autonomic nervous system's increase in blood pressure.

**Clinical Pearl / High-Yield Fact**
The autonomic nervous system's regulation of blood pressure is crucial in maintaining homeostasis, and imbalances in this regulation can lead to conditions such as hypertension and hypotension. Understanding the role of the sympathetic and parasympathetic nervous systems in blood pressure regulation is essential for diagnosing and treating these conditions.

**Correct Answer:** C. The renin-angiotensin-aldosterone system (RAAS) increases blood pressure.