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: $M ( x ) = 11 x - x ^ { 2 }$ . What rainfall produces the maximum number of mosquitoes?

A) $5.5 \mathrm { in } .$
B) $121 \mathrm { in. }$
C) 11 in.
D) 0 in.