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
In considering the process of eruption, the pre-functional eruptive stage of a tooth begins when the: 
Select and explain. 
A. Bud stage begins, B. Cap stage begins, C. Bell stage begins, D. Dental lamina begins forming
D: Dental lamina begins forming
Answer: D: Dental lamina begins forming 
Explanation: The dental lamina serves as the primordium of ectodermal portion of deciduous teeth. The permanent molars arise directly from a distal extension of dental lamina.