Match the following
$$\begin{array}{|cl|cl|}\hline
&\text{Heat treatment process} && \text{Effect}\\ \hline
P:& \text{Tempering} & 1.&\text{Strengthening} \\ \hline
Q:& \text{Quenching} & 2.&\text{Toughening} \\ \hline
R:& \text{Annealing} & 3.&\text{Hardening} \\ \hline
S:& \text{Normalizing} & 4.&\text{Softening} \\ \hline
\end{array}$$
- $P-2,\:Q-3,\:R-4\:,S-1$
- $P-1,\:Q-1,\:R-3\:,S-2$
- $P-3,\:Q-3,\:R-1\:,S-3$
- $P-4,\:Q-3,\:R-2\:,S-1$