The outputs of four systems $(S_{1}, S_{2}, S_{3},$ and $\text{S}_{4})$ corresponding to the input signal $\sin(t),$ for all time $t,$ are shown in the figure.
Based on the given information, which of the four systems is/are definitely $\text{NOT LTI}$ (linear and time-invariant)?
- $S_{1}$
- $S_{2}$
- $S_{3}$
- $S_{4}$