Which of the following is NOT a category of U.S. Navy ships?

Freighters are not categorized as U.S. Navy ships, which is why this is the correct choice. The U.S. Navy has specific classifications for its vessels, which include battleships, aircraft carriers, dock landing ships, and various other types designed for military purposes and operations.

Battleships are heavily armed and armored ships originally designed for naval warfare; however, they are no longer in active service but remain a category in historical and classification terms. Aircraft carriers serve as seagoing airbases, capable of deploying and recovering aircraft, and are critical for naval aviation operations. Dock landing ships support amphibious operations by transporting and landing troops, vehicles, and supplies directly onto shore.

Freighters, on the other hand, are commercial vessels used for transporting goods and cargo. They do not serve military functions within the Navy's operational framework and thus fall outside the categorization of Navy ships. This distinction reinforces the understanding of Navy classifications and their purposes in maritime strategy and operations.