The diffusion coefficients for species A in metal B are given at two temperatures: (a) Determine the value of the activation energy Qd (in J/mol). (b) Determine the value of D₀. a) (a) 25.6 kJ/mol; (b) 8.15 × 10⁻⁶ m²/s b) (a) 8.15 kJ/mol; (b) 25.6 × 10⁻⁶ m²/s c) (a) 25.6 kJ/mol; (b) 8.15 × 10⁻⁷ m²/s d) (a) 8.15 kJ/mol; (b) 25.6 × 10⁻⁷ m²/s