The Center of Mass of a Lamina in the Shape $r = \cos ( 2 \theta )$

Multiple Choice

The center of mass of a lamina in the shape of a region in the xy-plane bounded by $r = \cos ( 2 \theta )$ for the petal on the right with area density $\rho ( r , \theta ) = r$ is

A) $\left( \frac { 15 } { 28 } , \frac { 5 } { 8 } \right)$
B) $\left( 0 , \frac { 21 } { 10 } \right)$
C) $\left( \frac { 4 } { 5 } , \frac { 4 } { 5 } \right)$
D) $\left( \frac { 16 \sqrt { 2 } } { 35 } , 0 \right)$
E) $\left( \frac { 8 } { 5 } , \frac { 8 } { 5 } \right)$