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
Reccurent oral ulcers with pain and erythematous halo around them, diagnosis is: 
Select and explain. 
A. Apthus ulcer, B. Herpes, C. Chicken pox, D. Measels
A: Apthus ulcer
Answer: A: Apthus ulcer 
Explanation: A i.e. Apthous ulcer Apthous Ulcers Vitamine deficiency & Stress are impoant etiological agents Charecterstically presents with reccurent painful oral ulcers with erythema & halo around itQ.