The appropriate feedforward compensator, $G_{ff}$, in the shown block diagram is

1. $G_{ff} = \dfrac{2}{3}\dfrac{\left ( 8s + 1\right )}{\left ( 5s + 1\right )}$
1. $G_{ff} = -\dfrac{2}{3}\dfrac{\left ( 8s + 1\right )}{\left ( 5s + 1\right )}$
1. $G_{ff} = \dfrac{3}{2}\dfrac{\left ( 5s + 1\right )}{\left ( 8s + 1\right )}e^{-s}$
1. $G_{ff} = -\dfrac{3}{2}\dfrac{\left ( 5s + 1\right )}{\left ( 8s + 1\right )}e^{-s}$