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
Tooth eruption is due to 
Select and explain. 
A. Osteoclastic activity, B. Proliferation of cells at crypt, C. Exfoliation of primary tooth, D. Eruptive forces
D: Eruptive forces
Answer: D: Eruptive forces 
Explanation: None