Which of the following statements is/are true?

I. $$\frac{d}{dx}(x^2 \sin(x)) = 2x \sin(x) + x^2 \cos(x)$$

II. $$\frac{d}{dx}(\cos(3x^2)) = -3\sin(3x^2)$$

III. $$\frac{d}{dx}(\tan(x)) = \sec^2(x)$$