what are the passive properties of the membrane?

[Fa23]

Describe the contribution of passive electrical properties of membranes, to propagation of Action Potential along the myelinated axons.

I know how action potential is generated, what myelinated axons are, but I am just confused about the active and passive properties of the membrane. This was a test questions and I did horrible on it...4/10 I think, so any help would be very much appreciated. Thanks