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 primary dentition the anatomic structure used to
determine the molar relationship 
Select and explain. 
A. Mesio buccal cusp of primary 2nd molar, B. Distal plane of primary 1st molar, C. Mesial surface of primary 1st molar, D. Distal plane of primary 2nd molar
D: Distal plane of primary 2nd molar
Answer: D: Distal plane of primary 2nd molar 
Explanation: None