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': 'Hydatidiform-mole, blood cells does NOT develop because defect in \nSelect and explain. \nA. Primary ectoderm, B. Mesoderm, C. Endoderm, D. Trophoblast', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B. i.e. MesodermWhole cardiovascular system i.e. hea, bloodvessels, lymphatic & blood cellsQ are mesodermal in origin', 'role': 'assistant'}]