**Core Concept**
SLE-like reaction (systemic lupus erythematosus-like reaction) is a drug-induced autoimmune phenomenon characterized by fever, rash, arthralgia, serositis, and positive antinuclear antibodies, mimicking systemic lupus erythematosus. It is primarily mediated by the formation of immune complexes and activation of complement, often due to drug-induced autoantigen exposure.

**Why the Correct Answer is Right**
Hydralazine, a vasodilator used in hypertension, is a well-known cause of SLE-like reaction. It induces the formation of drug-antibody immune complexes, leading to complement activation and inflammation. This results in symptoms such as rash, arthralgia, serositis, and elevated antinuclear antibodies. The mechanism involves direct stimulation of autoantibody production and immune complex deposition in tissues.

**Why Each Wrong Option is Incorrect**
Option B: Rifampicin may cause hepatotoxicity or hypersensitivity, but not SLE-like reaction. It is not associated with immune complex formation leading to lupus-like features.
Option C: Paracetamol is generally safe and does not induce autoimmune phenomena. It is not linked to SLE-like reactions.
Option D: Furosemide causes electrolyte imbalances and gout, but not SLE-like features; it does not trigger immune complex formation.

**Clinical Pearl / High-Yield Fact**
Hydralazine is a classic drug that can trigger SLE-like syndrome, especially in patients with pre-existing autoimmune tendencies. Always consider drug-induced lupus in patients presenting with arthralgia, rash, and serositis, particularly after starting hydralazine or other hydralazine-like drugs.

✓ Correct Answer: A. Hydralazine