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
Systemic factor which is responsible for bone remodeling : 
Select and explain. 
A. IL-1,IL-6., B. TGF b., C. PGE2., D. PTH.
D: PTH.
Answer: D: PTH. 
Explanation: Regulatory Factors in Bone Remodelling