**Core Concept**
Tuberculosis (TB) of the bone and joint is a form of extrapulmonary tuberculosis that affects the musculoskeletal system. It can cause both destruction of bone and reduction of joint space due to the infection's destructive nature on the bone and cartilage.

**Why the Correct Answer is Right**
Tuberculosis of the bone and joint typically presents with pain, swelling, and limited mobility of the affected joint. The infection causes destruction of bone and cartilage through the action of Mycobacterium tuberculosis, leading to a reduction in joint space. This is due to the bacterial invasion of the synovial membrane and the subsequent inflammatory response, which results in the release of various cytokines and enzymes that break down the cartilage and bone. The destruction of bone and cartilage can lead to joint deformity and disability.

**Why Each Wrong Option is Incorrect**
**Option B:** Metastasis typically causes bone destruction through the formation of osteolytic lesions, but it does not typically reduce joint space.

**Option C:** Multiple myeloma is a malignancy of plasma cells that can cause bone destruction through the formation of osteolytic lesions, but it does not typically reduce joint space.

**Option D:** Lymphoma can cause joint pain and swelling, but it does not typically cause destruction of bone and reduction of joint space.

**Clinical Pearl / High-Yield Fact**
Tuberculosis of the bone and joint is a classic cause of a "cold" joint, meaning a joint that appears normal on imaging studies but is actually inflamed and painful.

**✓ Correct Answer: A. Tuberculosis**