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
[{'content': 'Which of the following condition can be responsible for heterotopic calcification in a 40 year old lady? \nSelect and explain. \nA. Gouty ahritis, B. Osteo ahritis, C. Reactive ahritis, D. Ankylosing spondylitis', 'role': 'user'}, {'content': "Answer: D \nExplanation: Heterotopic calcification means pathological calcification. It may be dystrophic or metastatic calcification. Calcification of the anterior spinal ligament occurs in ankylosing spondylitis which gives it the flowing wax appearance. Ref: Robbin's pathology, 6th Edition, Page 1252; Harrison 17th Edition, Page 2112", 'role': 'assistant'}]