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 a 9- year-old child, caries is commonly seen on: 
Select and explain. 
A. Occlusal surface of lower permanent first molar, B. Occlusal surface of upper permanent first molar, C. Distal surface of lower permanent first molar, D. Mesial surface of upper permanent first molar
A: Occlusal surface of lower permanent first molar
Answer: A: Occlusal surface of lower permanent first molar 
Explanation: None