Final answer:
The oldest active ship in the U.S. Navy's fleet is the a. USS Constitution, also known as 'Old Ironsides,' renowned for its speed and historical significance during the War of 1812.
Step-by-step explanation:
The oldest ship in the U.S. Navy's active fleet is USS Constitution. Known affectionately as "Old Ironsides," the USS Constitution is a storied warship with a rich history dating back to the early 19th century. It gained famous distinction during the War of 1812 against Britain, when under Captain Isaac Hull's command, it evaded a pursuing group of British ships for fifty-seven hours. This feat demonstrated not only the ship’s speed but also its resilience, as it was an American-designed and constructed frigate made from sturdy American oak. Its success in outsailing the best navy in the world at that time brought much-needed morale to Americans during the war.