How many LEDs does the control panel contain and what are the indicator colors?

• A. Eight LEDs: two red, two orange, two green, two blue
• B. Ten LEDs: one red, three orange, three green, three blue
• C. Seven LEDs: one red, two orange, two green, two blue
• D. Nine LEDs: one red danger, two orange warning/fail, two green safe/power, four detector head LEDs

Answer: (D)

The panel is designed for quick, at-a-glance status using a simple color scheme plus per-head indicators. There are nine LEDs in total: one red signals danger, two orange indicate warnings or faults, two green show safe status or power, and four LEDs are dedicated to the detector heads, one for each head. This arrangement lets you immediately see whether there’s a danger, a warning, normal operation, and the status of each detector individually. Other options don’t match this setup because they shift the total count or misallocate the per-head indicators, which breaks the panel’s intended clarity.