Which of the following allows the Coast Guard to board vessels without prior permission if suspected of enabling a terrorist act?

The correct choice is the Maritime Transportation Security Act (MTSA). This legislation was enacted to enhance security measures in the maritime sector, particularly in response to the heightened threat of terrorism. Under the MTSA, the Coast Guard is granted significant authority to board vessels to ensure compliance with security measures and to prevent acts of terrorism.

The act allows for boarding vessels without prior permission in specific situations where there is reasonable suspicion that the vessel may be involved in activities that could harm national security or public safety. This proactive approach is essential for protecting ports and waterways from potential threats.

While the Ports and Waterways Safety Act, Magnuson Act, and Homeland Security Act each address important aspects of maritime operations and security, none of them specifically provide the same level of authority to the Coast Guard for boarding vessels in response to suspected terrorist activities as the Maritime Transportation Security Act does.