Antiderivative Definite Integral And Average Value

Let the function $f$ be defined by $f(x) = 4x - 1$. Consider the following statements.

I. An antiderivative of $f$ is $2x^2 - x$.
II. $\int_0^2 (4x - 1)\,dx = 6$.
III. The average value of $f$ on the interval $[0, 2]$ is 3.

Which of the statements is/are correct?