) The following are solutions to the diffusion equation. Specify the best solution for each of the following examples and explain your choice. a) A thin sheet of steel (thickness 0.8 mm) with a high carbon concentration is annealed in a carbon-free gas environment for 2 weeks. The diffusion coefficient of C in steel is 10-7 cm2/s. b) A gas containing a dopant is passed over a Si wafer with thickness 0.1 cm for 30 minutes. The dopant diffusion coefficient is 10-10 cm2/s. c) A thin film of radioactive Fe is deposited on the and of a 40 mm long Fe cylinder and annealed at high temperature temperature for 60 minutes. The diffusion coefficient of Fe at this temperature is 10-9 cm2/s.