**Core Concept:** Gold salts are a group of medications primarily used in the treatment of rheumatoid arthritis and other autoimmune diseases. They work by inhibiting the activation of leukocytes, which reduces inflammation and pain. Gold salts are also known to suppress the immune system, which is why they are used in autoimmune diseases.

**Why the Correct Answer is Right:** Gold salts are primarily used in the treatment of rheumatoid arthritis (RA), a chronic autoimmune disease characterized by inflammation and joint destruction. Gold salts, specifically aurothioglucose, are administered intravenously and slowly absorbed into the body. They are effective in suppressing the immune system, preventing the activation of leukocytes, and thus reducing inflammation and pain associated with RA.

**Why Each Wrong Option is Incorrect:**

A. Gold salts are not used for psoriasis (skin disease) as they primarily target autoimmune diseases and not skin conditions.
B. Gold salts are not used for treating infectious diseases (e.g., tuberculosis, malaria) as they primarily target autoimmune diseases and have no direct antimicrobial properties.
C. Gold salts are not used for treating cancer, as their primary mode of action is on the immune system and not cytotoxic to cancer cells.
D. Gold salts are not used for treating migraines or other neurological disorders as they primarily target autoimmune diseases and have no direct effect on neurological symptoms.

**Clinical Pearl:** Gold salts are commonly associated with side effects like skin rash, gastrointestinal issues, and kidney damage due to their immunosuppressive effects, which highlights the importance of careful monitoring and patient education during treatment.

**Correct Answer:** C. Gold salts are used in the treatment of rheumatoid arthritis (RA).