$\begin {array} {1 1} (a)\;(\large\frac{P_A}{P_B})(\large\frac{M_A}{M_B})^{\frac{1}{2}}\\(b)\;(\large\frac{M_A}{M_B})(\large\frac{P_A}{P_B})^{\frac{1}{2}}\\(c)\;(\large\frac{P_A}{P_B})(\large\frac{M_B}{M_A})^{\frac{1}{2}}\\(d)\;(\large\frac{M_A}{M_B})(\large\frac{P_B}{P_A})^{\frac{1}{2}} \end {array}$