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: Pathology
Oral ulcers which occurs in groups, persist for about 6 weeks and leave scars on healing are: 
Select and explain. 
A. Recurrent aphthous major, B. Recurrent aphthous minor, C. Recurrent herpetiform ulcers, D. Acute herpetic gingivostomatitis
A: Recurrent aphthous major
Answer: A: Recurrent aphthous major 
Explanation: None