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: Surgery
[{'content': 'A 49 year old man suffering from carcinoma of prostate was x -rayed. He showed areas of sclerosis and collapse of T 10 and T11 veebrae in x-ray. The spread of this cancer to the above veebrae was through - \nSelect and explain. \nA. Sacral canal, B. Lymphatic vessels, C. Internal veebral plexus of veins, D. Superior rectal vein', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans is 'c' i.e. Internal veebral plexus of veins Prostatic cancer spreads to the bones through blood vessels; first into Batson's periprostatic venous plexus * and then into the internal veebral plexus of veins. This metastatis is possible because of valveless communication* between the periprostatic and veebral plexus of veins.", 'role': 'assistant'}]