A steam pipe is intended to be insulated with two layers of insulating materials of different thermal conductivities. For minimum heat transfer to take place

• A. the better insulation material should be put just next to pipe (i.e., inside).
• B. the better insulating material should be put outside.
• C. either of the insulating material could be put on either side.
• D. steam temperature is considered before deciding as to which insulating material is to be put inside (i.e., just next to the pipe).