The correct answer is the Hazard Communication Standard (HCS).

- The Hazard Communication Standard (HCS), established by OSHA, specifically requires that employers inform and train employees about the hazards associated with chemicals they may encounter in the workplace.
- This regulation ensures that workers have access to information such as chemical properties, potential health effects, protective measures, and emergency procedures.
- The key elements of the HCS include proper labeling of chemical containers, availability of Safety Data Sheets (SDS), and employee training programs.

In contrast, the other options focus on different aspects of workplace safety:
- Process Safety Management (PSM) deals primarily with the prevention of accidental releases of highly hazardous chemicals.
- Respiratory Protection Standard covers the use and maintenance of respirators to protect workers from airborne contaminants.
- Bloodborne Pathogens Standard governs protections related to exposure to infectious diseases through blood and bodily fluids.

Therefore, when it comes to ensuring employees are made aware of chemical hazards, the Hazard Communication Standard (HCS) is the governing OSHA regulation.

Reference: Occupational Safety and Health Administration Compliance Regulations, Volume 29 CFR Part 1910, Chapter 1910.1200 – Hazard Communication