单项选择题

A.G85 X50.0Y50.0 Z-10.0 R0 F50
B.G81 X50.0Y50.0 Z-10.0 R0 F50
C.G81 X50.0Y50.0 Z-10.0 R5.0F50
D.G83 X50.0Y50.0 Z-10.0 R5.0F50