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
Ca prostate commonly metastasises to the vertebrae - 
Select and explain. 
A. Because valveless communication exist with Batson' s periprostatic plexus., B. Via drainage to Sacral lymph node, C. Of direct Spread, D. None of above
A: Because valveless communication exist with Batson' s periprostatic plexus.
Answer: A: Because valveless communication exist with Batson' s periprostatic plexus. 
Explanation: None