Two systems $H_1(z)$ and $H_2(z)$ are connected in cascade as shown below. The overall output $y(n)$ is the same as the input $x(n)$ with a one unit delay. The transfer function of the second system $\mathrm{H}_2(z)$ is
- $\frac{\left(1-0.6 z^{-1}\right)}{z^{-1}\left(1-0.4 z^{-1}\right)}$
- $\frac{z^{-1}\left(1-0.6 z^{-1}\right)}{\left(1-0.4 z^{-1}\right)}$
- $\frac{z^{-1}\left(1-0.4 z^{-1}\right)}{\left(1-0.6 z^{-1}\right)}$
- $\frac{\left(1-0.4 z^{-1}\right)}{z^{-1}\left(1-0.6 z^{-1}\right)}$