The system I is described by the input$-$output retationship $a(t)=t-1,$ and the systom $2$ is

described by the input$-$autput relationship $\frac{t}{6}y(t)+2ty(t)=x(t),$ select the carrect statement

from the following choicies:

Siclect one:

System $1$ and system $2$ are linear:

b$.$ Syitem $1$ and system $2$ are time imvariant.

c$.$ System $17$ non$-$linitan and system $2$ is itime yorying.

d$.$ System $1$ in non$-$lusead, and $5$ istan $2$ is bint invariant.