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 of the following statements about Diploic veins are true, except: \nSelect and explain. \nA. Develop around 8th week of gestation, B. These have no valves (valveless), C. Present in cranial bones, D. Have a thin wall lined by a single layer of endothelium', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Diploic veins develop after bih and are not visible before 3 years of life. They fully develop only by 15 years of age. Ref: Freyschmidt\'s "Koehler/Zimmer" Borderlands of Normal and Early Pathologic By Jurgen Freyschmidt, Page 370; Atlas of Vascular Anatomy: An Angiographic Approach By Uflacker, 2nd Edition, Page 71; Tutorials in Endovascular Neurosurgery and Interventional Neuroradiology By James Vincent Byrne, Page 59; Atlas of Neuroradiologic Embryology, Anatomy and Variants By J. Randy Jinkins, Page 388', 'role': 'assistant'}]