According to data, the accident rate as a function of the age of the driver in years $x$ can be approximated by the function $f(x)=99\mathrm{.}6-2\mathrm{.}67x+0\mathrm{.}0291x^2-$ for $16x85.$ Find the age at which the accident rate is a minimum and the minimum rate.

How is the age determined for the age at which the accident rate is a minimum?

A$.$ Determine the $x-$value of the vertex.

B$.$ Substitute $0$ for $x$ and solve for $f(x).$

C$.$ Substitute $16$ for $x$ and solve for $f(x)$ because the minimum value of the function always occurs at the minimum value of $x$ in the interval.

D$.$ Determine the $y-$value of the vertex.

The age at which the accident rate is a minimum is $$

$($Round down to the nearest whole number.$)$