Khẳng định nào sau đây đúng?
A. \(\int\left(x-\dfrac{1}{x}\right)^2dx=\dfrac{x^3}{3}-2x-\dfrac{1}{x}+C.\)
B. \(\int\left(x-\dfrac{1}{x}\right)^2dx=\dfrac{x^3}{3}-2x+\dfrac{1}{x}+C.\)
C. \(\int\left(x-\dfrac{1}{x}\right)^2dx=\dfrac{1}{3}\left(x-\dfrac{1}{x}\right)^3+C.\)
D. \(\int\left(x-\dfrac{1}{x}\right)^2dx=\dfrac{1}{3}\left(x-\dfrac{1}{x}\right)^3\left(1+\dfrac{1}{x^2}\right)+C.\)