This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immune system, Subject name: Medicine
Ankylosing spondylitis may be associated with 
Select and explain. 
A. Atrial fibrillation, B. Pulmonary stenosis, C. Aoic incompetence, D. Mitral stenosis
C: Aoic incompetence
Answer: C: Aoic incompetence 
Explanation: Ref Davidson 23e p1030