Osteoarthritis is a degenerative joint disease characterized by the gradual breakdown of joint cartilage over time. It is not an autoimmune disease, and it does not involve inflammation like rheumatoid arthritis. While it can affect people of all ages, it is more commonly seen in older adults.

  
a. Osteoarthritis is not a systemic autoimmune disease. It is primarily a non-inflammatory condition, and the immune system is not involved in its pathogenesis.
b. Osteoarthritis is not a condition that primarily affects young adults. While it can occur at any age, it is more commonly seen in older individuals.
d. Osteoarthritis is not caused by the deposition of urate crystals. Urate crystal deposition is associated with gout, a different form of arthritis.