The boat command that means complete the stroke and level the oars horizontally with the blades trimmed fore and aft is（）.

A.using a rotary grinder with an installed shield
B.letting go the anchor
C.handling wire rope or natural fiber line
D.painting with a spray gun

A.flashing red lights
B.flashing green lights
C.white lights
D.yellow lights

A.Self-contained breathing apparatus with a lifeline attached
B.Combustible gas indicator
C.Rigid helmet，boots，and gloves
D.Flame safety lamp