$|$~$5||$ pts each $|||$ The graph of the derivative $f^{\text{'}}$ of a function $f$ is shown. Again, the graphamena the graph of the : $f^{\text{'}}$ of the function $f$ and not the graph of the function $f$ itself.

$($a$)$ Find all critical values of $f($just the $x-$values$)$ and classify each as a local maximum point of $f,$ a local minimum of $f,$ or neither.

$x=-2,$

$($b$)$ Give all intervals over which $f$ is decreasing.

$($c$)$ Determine all intervals over which $f$ is concave upward.

$($d$)$ State whether $f(1)f(4),$ or $f(1)=f(4).$ Brietly, explain your answer.

$8$