**Core Concept**
Seropositive rheumatoid arthritis (RA) is characterized by the presence of rheumatoid factor (RF) or anti-citrullinated protein antibodies (ACPAs) in the patient's serum. This distinction is crucial for diagnosis and treatment planning in RA.

**Why the Correct Answer is Right**
The presence of RF or ACPAs in seropositive RA indicates an autoimmune response against the patient's own tissues. This leads to inflammation and joint damage. RF is an antibody directed against the Fc region of IgG, while ACPAs target citrullinated proteins. Both are markers of a more aggressive disease course and are associated with the formation of immune complexes that deposit in the joints, leading to inflammation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not directly related to seropositive rheumatoid arthritis.
**Option B:** This option is incorrect as it is not a characteristic of seropositive rheumatoid arthritis.
**Option D:** This option is not a feature of seropositive rheumatoid arthritis.

**Clinical Pearl / High-Yield Fact**
The presence of RF or ACPAs in RA patients is a strong predictor of a more aggressive disease course and a poorer prognosis. This highlights the importance of early diagnosis and aggressive treatment in seropositive RA patients.

**Correct Answer:** C.