Answer
Choice C
Work Step by Step
The quadratic function, $f(x)=a(x-h)^2+k$ has vertex at $(h,k)$ and opens up if $a\gt0$ or opens down if $a\lt0$.
The given quadratic function, $
f(x)=-213(x-0.1)^2+3.6
$ has vertex at $(
0.1,3.6
)$ and opens down since $a\lt0$. Hence, $\text{
Choice C
.}$
