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
Age group for concrete operational stage: 
Select and explain. 
A. 0-2 yrs, B. 2-6 yrs, C. 7-12 yrs, D. 11-15 yrs
C: 7-12 yrs
Answer: C: 7-12 yrs 
Explanation: According to Piaget Cognitive theory, the sequence of development has been categorized into 4 major stages.
• Sensorimotor stage (0 to 2 yrs)
• Pre-operational stage (2 to 6 yrs)
• Concrete operational stage (7 to 12 yrs)
• Formal operational stage (11 to 15 yrs)