For \(-2.5 \lt x \lt 2.5\), let \(f\) be a continous function with first derivative given by \(f'(x)=e^{(x^4-2x^2+2)}-4 \). Which of the following are all intervals on which the graph of \(f\) is concave down?

The graph of \(f\) will be concave down when \(f'(x)\) is decreasing.

The graph of \(f'\) is shown below. Note that per the question the interval begins at \(-2.5\).