**Core Concept**
Botulinum toxin is a potent neurotoxin that acts by inhibiting the release of acetylcholine at the neuromuscular junction, thereby causing flaccid paralysis. This toxin specifically targets the presynaptic nerve terminals, preventing the vesicular release of neurotransmitters.

**Why the Correct Answer is Right**
The mechanism of botulinum toxin involves the binding of the toxin to the SNARE complex, which is essential for the fusion of vesicles with the presynaptic membrane. This binding event prevents the release of acetylcholine, leading to flaccid paralysis of the affected muscles. The toxin's effects are reversible, but the duration of paralysis depends on the amount of toxin released and the specific muscle affected. Botulinum toxin is used therapeutically for various conditions, including dystonia, spasticity, and hyperhidrosis.

**Why Each Wrong Option is Incorrect**
**Option A:** Botulinum toxin does affect the autonomic nervous system, including the parasympathetic and sympathetic divisions, which can lead to various systemic effects such as dry mouth, constipation, and orthostatic hypotension.
**Option B:** Botulinum toxin specifically targets the neuromuscular junction, causing flaccid paralysis of skeletal muscles, but it does not directly affect the central nervous system (CNS).
**Option C:** Botulinum toxin does not have a direct effect on the cardiovascular system, but it can cause systemic effects such as hypotension and bradycardia due to the inhibition of parasympathetic outflow.

**Clinical Pearl / High-Yield Fact**
Botulinum toxin is a reversible antagonist of acetylcholine release, making it a valuable therapeutic agent for various conditions. However, it is essential to be aware of the potential systemic effects and to use it judiciously in patients with underlying cardiovascular disease.

**Correct Answer:** B. Botulinum toxin does not directly affect the central nervous system (CNS).