Which of the following is an example of a physical barrier used in gas control?

The correct choice, which pertains to an example of a physical barrier used in gas control, involves the installation of sails. Physical barriers are tangible measures that inhibit or control the movement and release of gases, thereby reducing the risk of exposure or accidents.

In this context, sails or similar structures can serve to redirect gas away from certain areas or create physical obstructions that minimize the dispersion of hazardous gases in the environment. This approach is often vital in gas control strategies to protect personnel and the surrounding area from potential risks associated with gas leaks or emissions.

Other options, while important in their respective roles, do not represent physical barriers. Gas detectors are devices used for monitoring gas presence but do not physically obstruct gas movement. Emergency response plans outline procedures to respond to gas-related emergencies, and training programs ensure that personnel are knowledgeable about safety practices, but neither provides a physical barrier against gas itself. Thus, the installation of sails stands out as the correct example of a physical barrier in gas control.