【名词&注释】
恒牙萌出(tooth eruption)
[单选题]下颌恒牙萌出的顺序通常是
A. 6-1-2-3-4-5-7 B. 6-1-2-3-5-4-7 C. 6-1-2-4-3-5-7 D. 1-6-2-3-4-5-7 E. 1-2-6-4-3-5-7