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
Fibronectin is used in periodontal therapy as 
Select and explain. 
A. Growth factor, B. Bone graft, C. Biomodification of root surface, D. GTR membrane
C: Biomodification of root surface
Answer: C: Biomodification of root surface 
Explanation: None