Match the Machine Tools (Group A) with the probable Operations (Group B):

$$\begin{array}{|c|c|c|c|} \hline & \textbf{Group A} & & \textbf{Group B} \\ \hline P: & \text{Centre Lathe} & 1: & \text{Slotting} \\ \hline Q: & \text{Milling} & 2: & \text{Counter-boring} \\ \hline R: & \text{Grinding} & 3: & \text{Knurling} \\ \hline S: & \text{Drilling} & 4: & \text{Dressing} \\ \hline \end{array}$$

1. $P-1, Q-2, R-4, S-3$
2. $P-2, Q-1, R-4, S-3$
3. $P-3, Q-1, R-4, S-2$
4. $P-3, Q-4, R-2, S-1$