单项选择题

A.划线→锉削→锯割→钻孔→攻丝→弯折
B.划线→弯折→锯割→锉削→钻孔→攻丝
C.划线→锯割→锉削→弯折→划线→钻孔
D.划线→钻孔→套丝→锯割→锉削→弯折