A plane, solid slab of thickness L, shown in the figure, has thermal conductivity k that varies with the spatial coordinate x as k = A + B x, where A and B are positive constants ( A > 0, B > 0 ). The slab walls are maintained at fixed temperatures of T ( x = 0 ) = 0 and T ( x = L ) = T 0 > 0 The slab has no internal heat sources. Considering one-dimensional heat transfer, which one of the following plots qualitatively depicts the steady-state temperature distribution within the slab?