If a Is the Area of the Region Bounded by One

Multiple Choice

If A is the area of the region bounded by one petal of the four-petal rose $r = \cos 2 \theta,$ then A is

A) $\frac { \pi } { 8 }$
B) $\frac { \pi } { 6 }$
C) $\frac { \pi } { 4 }$
D) $\frac { \pi } { 2 }$
E) $\pi$