$\begin {array} {1 1} (a)\;\in_r=0.5, \mu_r = 1.5 & \quad (b)\;\in_r=1.5, \mu_r = 0.5 \\ (c)\;\in_r=0.5, \mu_r = 0.5 & \quad (d)\;\in_r=1.5, \mu_r = 1.5 \end {array}$