Final answer:
Iso-illuminance curves are drawings provided by luminaire manufacturers to assist with the placement and sizing of lighting fixtures. Therefore, the correct option is D.
Step-by-step explanation:
The correct answer is D) iso-illuminance curves. Iso-illuminance curves are drawings provided by luminaire manufacturers to assist with the placement and sizing of lighting fixtures. These curves show areas of equal illuminance, or light intensity, in a given space. By studying these curves, designers can determine the most effective placement of lighting fixtures to ensure uniform illumination in an area.