Final answer:
The Hazard Communication Standard (HCS), OSHA 1910.1200, is the regulation that first dealt with specific information about the contents of chemicals in the workplace.
Step-by-step explanation:
The right to know law under the Occupational Safety and Health Administration (OSHA) regulations that first dealt with specific information related to the contents of chemicals used in the workplace is known as the Hazard Communication Standard (HCS). The correct answer is C) OSHA 1910.1200. This particular regulation, introduced by OSHA, requires employers to inform their workers about chemical hazards through proper labeling and provision of safety data sheets, as well as providing necessary training. The aim is to ensure that employees understand the potential risks associated with chemicals in their work environment and how to handle them safely.