Zero reference for the GE LM2500 gas turbine engine is established by the use of which of the following engine components?

Correct Answer: Option A — Locking lug blades.

Locking lug blades serve as the zero reference point for the GE LM2500 compressor rotor. These specific blades are uniquely identified to establish a baseline for indexing during maintenance, borescope inspections, and blade replacement, ensuring precise alignment and tracking of the rotor assembly throughout the engine's operational life.