This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Development of GU system and Neuro-vascular supply of pelvis & perineum, Subject name: Anatomy
[{'content': 'Trigone of Urinary Bladder develops from ? \nSelect and explain. \nA. Mesoderm, B. Ectoderm, C. Endoderm of urachus, D. Endoderm of urogenital sinus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Trigone is derived from mesoderm although bladder is endodermal in origin. Intermediate mesoderm forms the Genito urinary system. Endoderm forms the urogenital sinus which forms urinary bladder and urethra.', 'role': 'assistant'}]