Final answer:
The NTSB, an independent U.S. agency, investigates civil transportation accidents involving aviation, railway, and shipping to promote safety and enforce regulations.
Step-by-step explanation:
The NTSB, or the National Transportation Safety Board, is an independent U.S. government agency responsible for civil transportation accident investigation. This includes aviation, railway, and shipping accidents. The agency's purpose is to investigate accidents, promote transportation safety, and make recommendations to improve safety in these industries. Investigating accidents is a keyword related to the NTSB's primary function, which includes enforcing regulations to protect those within the transportation industry and ensuring the safety of consumer goods or vehicles. Additionally, the NTSB works alongside other agencies, such as the U.S. Department of Transportation, which oversees the airline industry, and the National Highway Traffic Safety Administration which deals with motor vehicle accidents and safety.