An Architect Is Interested in Estimating the Rate of Heat

An architect is interested in estimating the rate of heat loss, ΔQ/Δt, through a sheet of insulating material as a function of the thickness of the sheet. Assuming fixed temperatures on the two faces of the sheet and steady state heat flow, which one of the graphs shown in the figure best represents the rate of heat transfer as a function of the thickness of the insulating sheet?

A) A
B) B
C) C
D) D
E) E