T1D05:When may amateur radio operators use their stations to notify other amateurs of the availability of equipment for sale or trade?
Direct answer summary (2026-2030 NCVEC pool)
The official correct answer for T1D05 is When selling amateur radio equipment and not on a regular basis.
The key fact is When selling amateur radio equipment and not on a regular basis. Match that fact to the exact condition in the question; the other choices describe a different rule, band, component, or operating situation.