According to the multi-stage pressure indicators, what background color indicates a pressure of 36% to 49%?

The correct choice reflects the specific designations of pressure levels in the multi-stage pressure indicators used in SCBA equipment. The background color associated with a pressure of 36% to 49% is yellow. This color coding system is essential for quick visual identification of remaining air supply, which is critical in emergency situations where every second counts.

The use of yellow specifically signifies a cautionary status, alerting the user that their air supply is becoming insufficient and that they may need to consider exiting the hazardous environment to ensure their safety. This standardized approach to color coding helps to avoid confusion and allows for immediate understanding of air supply status, which is crucial for effective decision-making while wearing the breathing apparatus.