The correct answer is number 3.- sketches.
When embarking on a project, Keith Harding uses sketches.
Keith Harding (1958-1990) was an urban artist that painted graffiti murals inthe subway stations in New York and he later became famous because of people’s acceptance of his work. He befriended with other artists form the underground art scene in New York like Kenny Sharf and Jean-Michelle Basquiat, which whom started painting graffiti in the city’s wall. Harding used sketches when he embarked on a project.