Answer:
The sentence "Free nations will press on to victory" relates to the central idea in the sense that:
b. It supports the main point that this is an ongoing fight that America will not abandon.
Explanation:
President Bush addresses how America has declared war against terror, and how that battle shall continue for as long as is necessary. Even though the troops are going home after serving, the mission continues. Terror is not over and, therefore, the war against it is also not over. America, as the free nation it is, will not accept terror to instigate fear among its people or to curb that people's freedom. When he says, "Free nations will press on to victory," he is supporting that point, the main one: the mission continues, the war against terror is not over. America will keep on fighting.
