With respect to fluid flow, match the following in Column $X$ with Column $Y$:

$$\begin{array}{|l|l|} \hline \qquad \textbf{Column X} & \qquad \textbf{Column Y} \\ \hline \text{(P) Viscosity} & \text{(I) Mach number} \\ \hline \text{(Q) Gravity} & \text{(II) Reynolds number} \\ \hline \text{(R) Compressibility} & \text{(III) Euler number } \\ \hline \text{(S) Pressure } & \text{(IV) Froude number} \\ \hline \end{array}$$

Which one of the following combinations is correct?

1. $\text{(P) – (II), (Q) – (IV), (R) – (I), (S) – (III)}$
2. $\text{(P) - (III), (Q) – (IV), (R) – (I), (S) – (II)}$
3. $\text{(P) - (IV), (Q) – (II), (R) – (I), (S) – (III)}$
4. $\text{(P) - (II), (Q) – (IV), (R) – (III), (S) – (I)}$