【名词&注释】
牙本质(dentin)、根管口(root canal orifice)、能力差(poor ability)、恒牙萌出(tooth eruption)
[单选题]上颌恒牙萌出(tooth eruption)时常见的顺序是
A. 6-1-2-3-4-5-7 B. 6-1-2-3-5-4-7 C. 6-1-2-4-5-3-7 D. 1-6-2-3-4-5-7 E. 1-2-6-4-3-5-7