Fixture wires used as pendant conductors for incandescent luminaires with intermediate or candelabra-base lampholders shall not be smaller than _____ AWG.
See answer and applicable Code reference
The correct answer is: b) 18
Article 410 covers the requirements for luminaires, lampholders and lamps. The rules for wiring are outlined in Part VI of this Article. As noted in Sec. 410.54(B), "Unless part of listed decorative lighting assemblies, pendant conductors shall not be smaller than 14 AWG for mogul-base or medium-base screw shell lampholders or smaller than 18 AWG for intermediate or candelabra-base lampholders."
See Sec. 402.6 for a similar requirement.