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: CARTS, WAGONS & SLEDS 
Clue: Used to transport small loads like lawn dirt, it's a cart with 1 tire & a shallow body, held & pushed by handles
a wheelbarrow

Category: THE INSTRUMENT OF DEATH 
Clue: In 1793 Jean-Paul Marat was retired in the bath with one of these
a knife

Category: CASTLING 
Clue: No castle is complete without this deep trench that prevents access from the surrounding land

a moat

