If the length of the minor axis of an ellipse is equal to half of the distance between the foci, then the eccentricity of the ellipse is:
\( \frac{\sqrt{5}}{3} \)
\( \frac{\sqrt{3}}{2} \)
\( \frac{1}{\sqrt{3}} \)
\( \frac{2}{\sqrt{5}} \)