Rheumatoid arthritis primarily affects which of the following?

Rheumatoid arthritis is an autoimmune disorder characterized by chronic inflammation primarily in the joints, but it has systemic implications that can affect various parts of the body. The condition not only leads to joint pain and swelling but can also impact other organs and systems, such as the heart, lungs, and eyes. This systemic involvement distinguishes rheumatoid arthritis from other forms of arthritis that primarily affect just the bones and joints.

The correct choice reflects the comprehensive nature of rheumatoid arthritis, highlighting that its effects extend beyond just the musculoskeletal system. This understanding is crucial for both diagnosis and management, as treatment strategies often need to address the broader implications of the disease on the entire body rather than just focusing on joint pain.