This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thorax, Subject name: Anatomy
[{'content': 'Ribs develop from: \nSelect and explain. \nA. Endothoracic fascia, B. Para-axial mesenchyme, C. Deep intercostal fascia, D. Superficial intercostal fascia', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. B Para-axial mesenchymeRef: Gray's Anatomy, 41st ed. pg. 212* The axial skeleton, vertebrae and ribs are derived from paraxial mesenchyme* The skull is derived from paraxial mesenchyme and neural crest mesenchyme* The skeletal elements in the limbs are derived from somatopleuric mesenchyme, which forms the limb buds.", 'role': 'assistant'}]