$4.$ A step function of size $2$ is applied to the set point of the control system shown in the figure. Kc $=1\mathrm{.}5$ and m $=1.$

a$)$ C$($s$)/$ R$($s$)$

b$)$ C $(\backslash$infty $)$

c$)$ Offset

d$)$ The maximum value of C and the time it occurs