This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolic disorders - 1, Subject name: Orthopaedics
[{'content': 'Features of Ankylosing spondylitis (AS) include all of the following EXCEPT: \nSelect and explain. \nA. Fibrous ankylosis is pa of pathogenesis of AS, B. Bony ankylosis is pa of pathogenesis of AS, C. Roos test is used to test for Sacroilitis, D. Marginal syndesmophytes are seen on X-ray', 'role': 'user'}, {'content': 'Answer: C \nExplanation: FEATURES of ankylosing spondilitis- enthesitis and this ultimately leads to joint ankylosis Both bony as well as fibrous ankylosis occurs in AS Marginal syndesmophytes are seen on X-ray Roos test is used for thoracic outlet syndrome.', 'role': 'assistant'}]