Which federal body regulates gas transmission and safety?

The Pipeline and Hazardous Materials Safety Administration (PHMSA) is the correct answer because it is the federal agency specifically tasked with regulating the safety of pipelines that transport gas and hazardous materials. PHMSA's primary responsibility includes setting and enforcing safety regulations that govern the construction, operation, and maintenance of these pipelines to ensure public safety and environmental protection.

In contrast, while the Environmental Protection Agency (EPA) oversees environmental regulations and policies, its role is not directly focused on the safety of gas transmission infrastructure. The Federal Energy Regulatory Commission (FERC) primarily regulates the transmission of electricity and gas in interstate commerce, including aspects like pricing and contracts, but does not handle safety. The Occupational Safety and Health Administration (OSHA) focuses on workplace safety across various industries rather than specifically regulating pipeline safety. This delineation of responsibilities highlights why PHMSA is the designated authority for gas transmission safety.