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
At 12 year age, 2nd mandibular molar will have? 
Select and explain. 
A. Crown complete with 1/3rd root, open apex, B. Crown complete with 3/4th root,, open apex, C. 3/4th crown completed, D. Crown complete with 1/4th root, open apex
B: Crown complete with 3/4th root,, open apex
Answer: B: Crown complete with 3/4th root,, open apex 
Explanation: None