In the diagram, \triangle{PQR} is equilateral and has side length 6\:cm. Each of the shaded triangles is equilateral and has side length 2\:cm. What fraction of the area of \triangle{PQR} is shaded?
Answer Choices
A. \frac37
B. \frac13
C. \frac12
D. \frac35
E. \frac23