Which code corresponds to the description 'Caution signal light control'?

• A. HE
• B. HG
• C. GK
• D. HS

Answer: (B)

Two-letter codes used in this material map directly to specific maintenance tasks within the signaling system. The description “Caution signal light control” points to the function that operates or controls the signal lights, specifically the caution aspect. In the standard coding scheme, the first letter identifies the broad area (signaling equipment), and the second letter designates the particular function within that area. The combination HG represents the signal-light control task, which aligns with controlling a caution signal light. That’s why this code is the best fit. The other codes refer to different tasks within the signaling or related subsystems and don’t describe the caution signal light control.