You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.

Category: POETS & POULTRY 
Clue: Last name of William Carlos, who wrote, "So much depends upon a red wheel barrow beside the white chickens"
williams

Category: THE CIVIL WAR 
Clue: A century before the U.S.S. Nautilus, the Confederacy had 2 of these new ships, the Pioneer  & the Hunley
submarines

Category: VIDEO GEOGRAPHY 
Clue: It's the "queen" of African waterfall royalty seen here

victoria falls