Which of the following is NOT one of the four lines of FAA business?

The assertion that the Commercial Transportation Office is not one of the four lines of FAA business is accurate. The FAA's primary lines of business include the Office of Airports (ARP), the Air Traffic Organization (ATO), and the Office of Commercial Space Transportation (AST).

The Office of Airports focuses on the oversight of airport development, ensuring safety, and funding programs; the Air Traffic Organization is responsible for managing air traffic control and air navigation services to ensure safety and efficiency in U.S. airspace; while the Office of Commercial Space Transportation regulates and promotes the U.S. commercial space transportation industry.

In contrast, there is no recognized line of business specifically designated as the Commercial Transportation Office within the FAA’s organizational structure, making it distinct from the primary lines that contribute to the FAA's core mission.