For the differentiable function g, the derivative is g′(x)=x3−6x. The second derivative is g′′(x)=3x2−6. Which of the following correctly classifies the critical points of g?
a) Relative maximum at x=0; relative minima only at x=6.
b) Relative maxima at x=0; relative minima at x=6 and x=−6.
c) Relative minima at x=0; relative maxima at x=6 and x=−6.
d) Relative maxima at x=0; relative minima at x=2 and x=−2.