With respect to metal working, match Group A with Group B:

$$\begin{array}{|l|l|l|l|} \hline & \textbf{Group A} && \textbf{Group B} \\ \hline P. & \text{Defect in extrusion} & I: & \text{alligatoring} \\ \hline Q: & \text{Defect in rolling} & II: & \text{scab} \\ \hline R: & \text{Product of skew rolling} & III: & \text{fish tail} \\ \hline S: & \text{Product of rolling through cluster mill} & IV: & \text{seamless tube}\\ \hline && V: & \text{thin sheet with tight tolerance} \\ \hline && VI: & \text{semi-finished balls of ball bearing} \\ \hline \end{array}$$

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