What government agency is responsible for maintaining a safe and healthy work environment within the Department of Labor?

The Occupational Safety and Health Administration (OSHA) is the correct answer because it is specifically tasked with ensuring safe and healthy working conditions by setting and enforcing standards and providing training, outreach, education, and assistance. Its primary focus is to prevent workplace hazards and protect employees from unsafe working environments within all sectors of the economy, including those governed by the Department of Labor. OSHA's regulations cover a wide range of issues, such as exposure to harmful substances, machine safety, and fall protection, making it the key agency for workplace safety.

The other agencies listed are related to health and environmental issues but do not directly oversee workplace safety within the context specified. The Environmental Protection Agency, for example, focuses on environmental protection and regulation, while the National Institute for Occupational Safety and Health conducts research and provides recommendations for preventing work-related injuries and illnesses. The Department of Health and Human Services oversees various aspects of public health but does not specifically regulate workplace safety, leaving OSHA as the primary authority in that domain.