Match the entries in $\text{Group I}$ with the process parameters in $\text{Group II}$.

$\begin{array}{|C|l|C|l|} \hline &\textbf{Group I} & {} & \text{Group II} \\\hline P. &\text{Clark electrode} & 1. &\text{Liquid level} \\\hline Q. &\text{Redox probe} & 2. &\text{Dissolved oxygen concentration} \\\hline R. &\text{Load cell} & 3. &\text{Vessel pressure} \\\hline S. &\text{Diaphragm gauge} & 4. &\text{pH (anaerobic process)} \\\hline\end{array}$

1. $\text{P-2, Q-1, R-3, S-4}$
2. $\text{P_4, Q-2, R-3, S-1}$
3. $\text{P-2, Q-4, R-1, S-3}$
4. $\text{P-2, Q-1, R-4, S-3}$