Consider two functions \[f(x) = a - x^2,\] \[g(x) = x^4 - a.\]

For precisely which values of \(a > 0\) is the area of the region bounded by the \(x\)-axis and the curve \(y = f(x)\) bigger than the area of the region bounded by the \(x\)-axis and curve \(y = g(x)\)?

- all values of \(a\),
- \(a > 1\),
- \(a > \dfrac{6}{5}\),
- \(a > \left(\dfrac{4}{3}\right)^{3/2}\),
- \(a > \left(\dfrac{6}{5}\right)^4\).