【单选题】

As necessary, use the applicable SAFETY BARRIERS, specified by the operator's instructions and your local regulations. These communications are subjected to atmospheric disturbances and difficult to understanD.

A、As necessary, use the applicable SAFETY BARRIERS, classified by the operator's instructions and your local regulations. These communications are subjected to atmospheric interference and difficult to understanD.
B、Use the applicable SAFETY BARRIERS, specified by the operator's instructions and your local regulations if necessary. These communications are affected by the atmosphere and difficult to understanD.
C、Use the applicable SAFETY BARRIERS, classified by the operator's instructions and your local regulations if necessary. These communications are subjected to atmospheric interference and difficult to understanD.