Variation of current passing through a conductor as the voltage applied across its ends as varied is shown in the adjoining diagram. If the resistance (R) is determined at the points A, B, C and D, we will find that

From the curve it is clear that slopes at points A, B, C, D have following order A > B > C > D and also resistance at any point equals to slope of the V-i curve. So order of resistance at three points will be  

$R_A>R_B>R_C>R_D$