Where are the "Nodes of Ranvier" found?

In the following list,how many structures are included in grey matter?
Cell body,myelinated axon,unmyelinated axon,and dendron.

The largest cell in the human body is:

Four healthy people in their twenties faced injuries resulting in damage and death of a few cells given below. Which of the cells are least likely to be replaced by new cells?

Select the correct option for dendrites and axons.
$I -$ Short fibers,$II -$ Long fibers,$III -$ Transmit impulses away from the cell body,$IV -$ Transmit impulses towards the cell body,$V -$ Highly branched fibers,$VI -$ Unbranched fibers
Dendrites $\quad$ $\quad$ Axon

What does a neuron consist of?