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: Medicine
Pulmonary embolism is most commonly produced by which of the following - 
Select and explain. 
A. Trauma, B. Atherosclerosis, C. Thrombosis of pelvic vessels, D. None
C: Thrombosis of pelvic vessels
Answer: C: Thrombosis of pelvic vessels 
Explanation: None