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)