Choose the option that correctly matches the step response curve on the left with the appropriate transfer functions on the right. The step input change occurs at time $t=0$.

1. $P-III$, $Q-IV$, $R-II$, $S-I$
2. $P-III$, $Q-I$, $R-IV$, $S-II$
3. $P-IV$, $Q-III$, $R-II$, $S-I$
4. $P-III$, $Q-II$, $R-IV$, $S-I$