Match Group A with Group B:

$\begin{array}{|l|l|} \hline \textbf{Group A} & \textbf{Group B} \\ \hline \text{P: Biot number} & \text{1: Ratio of buoyancy to viscous force} \\ \hline \text{Q: Grashof number} & \text{2: Ratio of inertia force to viscous force} \\ \hline \text{R: Prandtl number} & \text{3: Ratio of momentum to thermal diffusivities} \\ \hline \text{S: Reynolds number} & \text{4: Ratio of internal thermal resistance to } \\ {} & \text{ boundary layer thermal resistance}\\ \hline \end{array}$

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