When a function is reflected over the x-axis, all the y-values change their signal.
In order to find the new function, we just need to do f'(x) = -f(x), this way we change the signal of the y-values.
So we have:
[tex]\begin{gathered} f(x)=-3(x+2)^2 \\ f^{\prime}(x)=-f(x) \\ f^{\prime}(x)=3(x+2)^3 \end{gathered}[/tex]
Therefore the correct option is B.
