This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urology, Subject name: Anatomy
A 49-year-old man suffering from carcinoma of the prostate was x -rayed. He showed areas of sclerosis and collapse of T10 and T11 veebrae in x-ray. The spread of this cancer to the above veebrae was through - 
Select and explain. 
A. Sacral canal, B. Lymphatic vessels, C. Internal veebral plexus of veins, D. Superior rectal vein
C: Internal veebral plexus of veins
Answer: C: Internal veebral plexus of veins 
Explanation: 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 metastasis is possible because of valveless communication between the periprostatic and veebral plexus of veins. Ref : S. Das Textbook of Surgery, 3/e p1247