Which agency was created to help prevent terrorist attacks in the U.S. following the Homeland Security Act of 2002?

The Department of Homeland Security (DHS) was established as a direct response to the September 11, 2001, terrorist attacks, with the primary goal of preventing future terrorism and ensuring the nation's security. Formed by the Homeland Security Act of 2002, the DHS consolidated numerous existing federal agencies under one umbrella to improve coordination and communication in the fight against terrorism. This agency oversees various functions, including the protection of the nation’s borders, transportation security, emergency management, and cybersecurity efforts.

While other agencies mentioned do play significant roles in aviation safety and national security, the DHS is specifically tailored to oversee and implement policies developed to mitigate terrorism risks on a broader scale, making it the appropriate answer to the question regarding the agency created to prevent terrorist attacks after the establishment of the Homeland Security Act.