**Core Concept**
Lyme disease is a tick-borne illness caused by the bacterium *Borrelia burgdorferi*. Stage III of Lyme disease is characterized by the involvement of the central nervous system and the heart.

**Why the Correct Answer is Right**
In Stage III, also known as neuroborreliosis, the bacteria *Borrelia burgdorferi* invade the central nervous system, leading to inflammation and damage to the brain and spinal cord. This can result in symptoms such as encephalitis, meningitis, and radiculopathy. The heart involvement in Stage III is manifested as Lyme carditis, which can cause symptoms such as pericarditis and atrioventricular block.

**Why Each Wrong Option is Incorrect**
**Option A:** This option might be referring to Stage I of Lyme disease, which is characterized by a skin rash known as erythema migrans.
**Option B:** This option might be referring to Stage II of Lyme disease, which is characterized by joint inflammation and arthritis.
**Option C:** This option is incorrect because it does not accurately describe Stage III of Lyme disease.

**Clinical Pearl / High-Yield Fact**
The characteristic rash of Lyme disease, erythema migrans, often expands over a period of days or weeks, and may have a "bull's-eye" appearance.

**Correct Answer:** C.