Points A and C lie on a circle centered at O, each of \overline{B A} and \overline{B C} are tangent to the circle, and \triangle A B C is equilateral. The circle intersects \overline{B O} at D. What is \dfrac{B D}{B O} ?
Answer Choices
A. \dfrac{\sqrt{2}}{3}
B. \dfrac{1}{2}
C. \dfrac{\sqrt{3}}{3}
D. \dfrac{\sqrt{2}}{2}
E. \dfrac{\sqrt{3}}{2}