This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Skin
An auto immune disease is: 
Select and explain. 
A. Pemphigus Vulgaris, B. Psoriasis, C. Lichen Planus, D. Acne Vulgaris
A: Pemphigus Vulgaris
Answer: A: Pemphigus Vulgaris 
Explanation: A i.e. Pemphigus vulgarisDiseaseEtiologyPemphigusPemphigoid, Epidermolysis bullosa acquisitaAutoinimune(2Lichen planusInflamatory disorder of unknown originAcne vulgarisObstruction of pilo-sebaceous gland.QEpidermolysis bullosa congenitaPsoriasisGenetic diseaseQ of unknown originGenetic dsQ unknown (inflamatory) origin