Final answer:
Hazardous Communication Plans describe issues with exposure to hazardous substances and are a requirement for workplaces to ensure employee safety, as mandated by OSHA.
Step-by-step explanation:
Hazardous Communication Plans primarily describe issues with possible exposure to C) Hazardous substances. These plans are integral to a workplace as they provide information about the chemicals workers may be exposed to, and outline the methods employers must use to inform their workers about chemical hazards. Some of these methods include training, using labels, alarms, color-coded systems, and chemical information sheets. It is part of an employer's responsibility under OSHA regulations to not only inform workers of potential hazards but also to reduce or eliminate these hazards by making changes in working conditions wherever possible, before relying on personal protective equipment.