Heat transfer by conduction results due to the transfer of free electrons, kinetic energy & vibrational energy from one molecule to another. Conduction heat transfer cannot take place

Between two bodies in physical contact with each other

Between two bodies not in physical contact with each other

From one part of a body to the another part of the same body

Both $\text{'}$b$\text{'}$ & $\text{'}$c$\text{'}$