Which agency was established under the federal Department of Labor to ensure safe working conditions?

The correct choice is OSHA, which stands for the Occupational Safety and Health Administration. OSHA was created in 1970 as part of the Occupational Safety and Health Act, with the primary mission of ensuring safe and healthy working conditions for employees in the United States. This agency sets and enforces workplace safety standards, provides training, outreach, education, and assistance to employers and employees. OSHA’s role is critical in preventing workplace injuries, illnesses, and fatalities, making it a cornerstone of occupational safety in various industries, including those involving hazardous materials or environments.

The other agencies mentioned have different focuses: the EPA (Environmental Protection Agency) is dedicated to environmental protection, NIOSH (National Institute for Occupational Safety and Health) conducts research and makes recommendations for the prevention of work-related injury and illness but does not enforce standards, and FMCSA (Federal Motor Carrier Safety Administration) primarily deals with regulations for the trucking industry and large commercial vehicles, rather than general workplace safety. Each agency plays an important role in its respective area, but OSHA specifically targets workplace safety regulations and enforcement.