To determine the length constant, or space constant, you can inject current (without activating an action potential) and plot (Vr is the resting membrane potential; electrotonus is the steady-state voltage)
A) Ln (V - Vr) vs x during conditions of electrotonus B) Ln (V - Vr) vs t during conditions of electrotonus C) Ln (V - Vr) vs t during the rise phase or decline phase of electrotonus D) Ln (V - Vr) vs t only during the decline phase of electrotonus E) Ln (V - Vr) vs t only during the rise phase of electrotonus