Find the Area of the Shaded Region $\mathrm { mm } ^ { 2 }$

Multiple Choice

Find the area of the shaded region.

A) 6 $\mathrm { mm } ^ { 2 }$
B) 12 $\mathrm { mm } ^ { 2 }$
C) 18 $\mathrm { mm } ^ { 2 }$
D) 36 $\mathrm { mm } ^ { 2 }$
E) 72 $\mathrm { mm } ^ { 2 }$