The diffusion equationsɎ²t + q g = (1/α) (d t/d r)Governs the temperature distribution under unsteady heat flow through a homogenous and isotropic material. The Fourier equation follows from this expression when

• A. Temperature doesn’t depends on time
• B. There is no internal heat generation
• C. Steady state conditions prevail
• D. There is no internal heat generation but unsteady state condition prevails