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
According to Stone and Church's classification, John, age
4, can be classified developmentally as: 
Select and explain. 
A. Toddler, B. Preschooler, C. Middle years child, D. Adolescent
B: Preschooler
Answer: B: Preschooler 
Explanation: None