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: Dental
Which growth factor Is not present in PRP? 
Select and explain. 
A. PDGF aa, B. PDGF bb, C. PDGF cc, D. PDGF Fab
C: PDGF cc
Answer: C: PDGF cc 
Explanation: None