Rheumatoid arthritis (RA) is a chronic autoimmune disease that primarily affects the joints. It is characterized by symmetric synovitis, which means that the inflammation occurs in the same joints on both sides of the body. Joint erosion is another characteristic of RA, where the inflammation leads to the destruction of the joint cartilage and bone. Additionally, RA can also have multisystem extra articular manifestations, meaning that it can affect other parts of the body besides the joints, such as the skin, eyes, heart, and lungs. Therefore, the correct answer is "all of the above."