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
Alopecia areata is a/ an ? 
Select and explain. 
A. Autoimmune disorder, B. Allergic disorder, C. Anaphylactic disorder, D. Bacterial infection
A: Autoimmune disorder
Answer: A: Autoimmune disorder 
Explanation: Ans. is 'a' i.e., Autoimmune disorder