Which of the following is true regarding the installation of shutoff valves?

The requirement that shutoff valves must be readily accessible is crucial for safety and convenience during maintenance or emergency situations. By having them located no less than 6 feet from any appliance, it allows for quick access without being too close to the appliance itself, which could pose safety hazards during operation or in the event of a malfunction.

This accessibility ensures that users can easily turn off the gas supply in case of a leak or other emergency, ultimately contributing to better safety in residential and commercial settings. Additionally, by specifying a distance from appliances, it helps regulate installation practices to avoid hazardous situations, thereby complying with regulatory codes and standards.

The other options present limitations or inaccuracies regarding the placement of shutoff valves that do not align with best safety practices or code requirements.