In a composite slab, the temperature at the interface (Tinter) between two materials is equal to average of the temperatures at the two ends. Assuming steady one dimensional heat conduction, which of the following statements is true about the respective thermal conductivities.
(a) 2K1 = K2 (b) K1 = K2
(c) 2K1 = 3K2 (d) K1 = 2K2