This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nephrotic and Nephritic syndrome, Subject name: Medicine
Which nephritogenic antigen is detected in subepithelial humps of PSGN? 
Select and explain. 
A. Streptococcal pyrogenic exotoxin B, B. Nephritis associated plasmin receptor, C. M antigen, D. P antigen
A: Streptococcal pyrogenic exotoxin B
Answer: A: Streptococcal pyrogenic exotoxin B 
Explanation: RF: Type II HSR PSGN: Type III HSR