Final answer:
D) arthritis. The MOST common age-related disease is arthritis. It involves inflammation of the joint, causing pain, swelling, stiffness, and reduced joint mobility.
Step-by-step explanation:
According to the information provided, the MOST common age-related disease is arthritis. Arthritis is a common disorder of synovial joints that involves inflammation of the joint, resulting in significant joint pain, swelling, stiffness, and reduced joint mobility. There are more than 100 different forms of arthritis, and it can arise from various causes such as aging, damage to the articular cartilage, autoimmune diseases, bacterial or viral infections, or genetic factors.