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
Ratio of Pleural Fluid protein to serum protein is _______ in transudative pleural effusion 
Select and explain. 
A. < 0.3, B. < 0.4, C. < 0.5, D. < 0.6
C: < 0.5
Answer: C: < 0.5 
Explanation: Pleural Fluid Protein / Serum. Protein is < 0.5 in transudative effusion.