【单选题】

Solenoid valves shall be shown with a notation indicating whether the valve is spring-loaded to the open or closed position.

A、Solenoid valves shall be shown with a notation. The notation indicates the spring is loaded by the valve to the open or closed position.
B、Solenoid valves shall be shown with a symbol. The valve indicates whether the valve is spring-loaded to the open or closed position.
C、Solenoid valves shall be shown with a mark. The mark indicates whether the valve is spring-loaded to the open or closed position.