Zero reference for the LM2500 GTE is established by the use of which of the following engine components?

Correct Answer: Option A — Locking lug blades.

The locking lug blade serves as the zero reference point for the LM2500 rotor assembly. This specific blade is used to establish the starting position for indexing and mapping the compressor and turbine stages, ensuring that all inspection findings are accurately recorded relative to a known, fixed engine position.