Solve the Problem $\mathrm { M } ( \mathrm { x } )$

Multiple Choice

Solve the problem.
-The number of mosquitoes $\mathrm { M } ( \mathrm { x } )$ , in millions, in a certain area depends on the June rainfall $x$ , in inches: $\mathrm { M } ( \mathrm { x } ) =$ $14 x - x ^ { 2 }$ . What rainfall produces the maximum number of mosquitoes?

A) $0 \mathrm { in }$ .
B) $14 \mathrm { in. }$
C) $196 \mathrm { in } .$
D) $7 \mathrm { in }$ .