n the following lines from O Captain! my Captain!, what is the prize that the speaker mentions?

O Captain! my Captain! our fearful trip is done,
The ship has weather’d every rack, the prize we sought is won,

The ship fought valiantly, or with honor, but was lost at sea.

The ship has returned to port with the spoils of war from a conquered land.

The United States has won independence from Britain and is now a sovereign nation.

The United States has weathered the storm of the Civil War and remained unite