Write the equation of the graph shown below in factored form.
f(x) = (x + 1)(x − 2)(x − 3)
f(x) = (x − 1)(x + 2)(x + 3)
f(x) = (x + 1)(x + 2)(x + 3)
f(x) = (x − 1)(x − 2)(x − 3)