对形状复杂，截面变化大的零件进行淬火时，应选用（ ）。

A、高淬透性钢

B、<span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">中淬透性钢</span>

C、<span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">低淬透性钢</span>

D、<span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">淬透性要求无明显区别</span>

B、<span style="FONT-FAMILY: 宋体; mso-ascii-font-family: \'Times New Roman\'; mso-hansi-font-family: \'Times New Roman\'">中淬透性钢</span>

C、<span style="FONT-FAMILY: 宋体; mso-ascii-font-family: \'Times New Roman\'; mso-hansi-font-family: \'Times New Roman\'">低淬透性钢</span>

D、<span style="FONT-FAMILY: 宋体; mso-ascii-font-family: \'Times New Roman\'; mso-hansi-font-family: \'Times New Roman\'">淬透性要求无明显区别</span>