Five rods of the same dimension are arranged as shown . AB are maintained at different temperatures . No Heat flows through the central rod ; then

Question

$(a)\;K_{1}K_{4}=K_{2}K_{3}\qquad(b)\;K_{1}K_{2}=K_{3}K_{4}\qquad(c)\;K_{1}K_{3}=K_{2}K_{1}\qquad(d)\;None$