According to NFPA 70, abrasion protection shall be applied to what component where it passes...

The correct answer isA. According toNFPA 70, when aconductorpasses throughmetal, protection must be provided so that theconductor insulationis not damaged by sharp edges, burrs, or vibration at the metal opening. The concern is not the conduit itself, but theinsulated conductor surface, because abrasion at the point of entry can wear through the insulation and create a risk of short circuit, ground fault, arcing, or shock hazard. This is why bushings, grommets, insulated fittings, or other approved protective means are commonly required wherever insulated conductors pass through sheet metal, boxes, cabinets, gutters, or similar metallic openings.

The other options are incorrect becauserigid conduitandsemi-rigid conduitare wiring methods, not the protected element identified in this rule.Secondary circuitsare a circuit classification, not the physical component being protected from abrasion. In API-aligned source inspection and quality surveillance, this requirement is important when verifying panel wiring, junction boxes, control panels, and other electrical assemblies to ensure conductor routing and entry points comply with code and do not damage the insulation during service. Therefore, the correct answer isconductor insulation.