Heat transfer. Select in which conditions this equation can be used: 1 (kr r dr -) + dr (k)+e =0 gen A 2-D steady conduction with heat generation and variable thermal conductivity B 2-D transient conduction with heat generation and variable thermal conductivity C 3D steady conduction with heat generation and variable thermal conductivity 2-D transient conduction with heat generation and constant thermal conductivity E 2-D steady conduction with heat generation and constant thermal conductivity