On an LM2500 gas turbine powered vessel you are conducting a borescope inspection of the compressor. What is used on each compressor stage as a reference for indexing the blades?

Correct Answer: Option B — The locking lug blades.

Locking lug blades are specifically designed with unique features to serve as a reference point for indexing during inspections. By identifying the locking lug, the technician can accurately count and map the position of other blades around the rotor circumference, ensuring a systematic and repeatable inspection of all blades.