What was the United States' military operation in response to the 2004 Indian Ocean tsunami?

The correct choice is Operation Unified Assistance because it specifically refers to the coordinated military and humanitarian response by the United States and other nations following the devastating Indian Ocean tsunami in December 2004. This operation involved deploying resources, personnel, and supplies to aid countries affected by the disaster, such as Indonesia, Sri Lanka, and Thailand.

Operation Unified Assistance highlighted the U.S. military's capacity to mobilize for humanitarian missions on a large scale, showcasing the importance of international cooperation in disaster relief efforts. The operation involved various branches of the military and aimed to provide immediate support to those in need, demonstrating the U.S. commitment to humanitarian assistance in the wake of natural disasters.

The other options, while significant military operations, are not directly related to the tsunami. Operation Iraqi Freedom pertains to the Iraq War, and Operation Enduring Freedom relates to the campaign against terrorism in Afghanistan and surrounding regions. Operation Tsunami Relief is a term that might refer to various relief efforts but is not the official title of the operation conducted by the U.S. military in this context.