Let a spherical block of ice at $-7^{\circ} \mathrm{C}$ be exposed to atmospheric air at $30^{\circ} \mathrm{C}$ with the gravitational direction as shown in the figure below. What will be the overall direction of air flow in this situation?

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 + Bx, 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) = T₀ > 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?