The Number of Mosquitoes $M(x)$ , in Millions, in a Certain Area Depends on the Certain

Multiple Choice

The number of mosquitoes $M(x)$ , in millions, in a certain area depends on the June rainfall $x$ , in inches, according to the function $\mathrm{M}(\mathrm{x}) =6 \mathrm{x}-\mathrm{x}^{2}$ . What rainfall produœes the maximum number of mosquitoes?

A) $36 \mathrm{in}$ .
B) 3 in.
C) 0 in.
D) 6 in.