Question Detail

To find the derivative of y = sec ax, we use the chain rule.Recall the derivative of sec(u) with respect to u is sec(u) tan(u).Here, let u = ax.Then, du/dx = d/dx (ax) = a.Applying the chain rule:dy/dx = d/dx [sec(ax)] = sec(ax) tan(ax) * d/dx(ax) = sec(ax) tan(ax) * a = a sec ax tan ax.This matches option C.