Each side of the large square in the figure is trisected (divided into three equal parts). The corners of an inscribed square are at these trisection points, as shown. The ratio of the area of the inscribed square to the area of the large square is
Answer Choices
A. \dfrac{\sqrt{3}}{3}
B. \dfrac{5}{9}
C. \dfrac{2}{3}
D. \dfrac{\sqrt{5}}{3}
E. \dfrac{7}{9}