As shown in the figure, two rods of different metals of equal lengths L/2, diameter d (d << L), and constant thermal conductivities k₁ and k₂ (with k₁ > k₂) are connected perfectly (i.e., zero interface thermal resistance). The left and right ends of the connected rod are maintained at temperatures T₁ and T₂ (T₁ > T₂). Assume that the rods are insulated from the environment, apart from the two flat ends. Which one of the following graphs represents the temperature distribution at steady-state? The thickest line shows the temperature profile. The horizontal axis shows the distance from the left end of the rod to the right and the vertical axis denotes temperature.