The small-signal resistance (i.e., dV_B/dI_D) in kΩ offered by the n-channel MOSFET M shown in the figure below, at a bias point of V_B = 2 V is (device data for M: device transconductance parameter k_N = μ_nC_ox(W/L) = 40 μA/V², threshold voltage V_TN = 1 V, and neglect body effect and channel length modulation effects)