The length of the chord of the ellipse \( \displaystyle\frac{x^2}{4} + \frac{y^2}{2} = 1 \), whose mid-point is \(\displaystyle \left( 1, \frac{1}{2} \right) \), is:
\( \dfrac{2}{3}\sqrt{15} \)
\( \dfrac{1}{3}\sqrt{15} \)
\( \dfrac{5}{3}\sqrt{15} \)
\( \sqrt{15} \)