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: Anatomy
[{'content': 'All are true regarding the trigone of the urinary bladder except- \nSelect and explain. \nA. Mucosa is loosely associated to the underlying musculature, B. Mucosa is smooth, C. It is lined by transitional epithelium, D. It is derived from the absorbed part of the mesonephric duct', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Mucosa is firmly attached to the underlying musculature.', 'role': 'assistant'}]