What is the pressure rating of the SCBA air cylinder?

The correct pressure rating of the SCBA (Self-Contained Breathing Apparatus) air cylinder is 4500 psig. This rating is significant as it directly relates to the performance and safety of the SCBA when used in fire and hazardous environments. A pressure of 4500 psig allows for an adequate air supply for firefighters, ensuring they can operate effectively while minimizing weight and maximizing the duration of use.

Higher pressures, such as those found in the other options, are not standard for SCBA cylinders due to safety and design limitations. These cylinders must be designed to withstand specific pressures and provide reliable functionality without posing unnecessary risks to the user. Therefore, 4500 psig is the optimal balance of air supply and safety for firefighters in the field.