If $z_1,z_2$ are complex numbers such that $\large\frac{2z_1}{3z_2}$ is purely imaginary the the value of $\bigg|\large\frac{z_1-z_2}{z_1+z_2}\bigg|$ is ?

Question

$\begin{array}{1 1}(A) 1 \\(B) 0 \\ (C) \large\frac{2}{3} \\ (D) \large\frac{3}{2} \end{array}$