Afatty material called insulates and protects some axons.
a. schwann cells
b. myelin
c. interneurons
d. nodes

b. myelin

Explanation:

Most motor neuron axons are myelinated, meaning they are covered by a myelin sheath, which is a “fatty” substance that isolates and protects the neuron's cell membrane. In the peripheral nervous system, this myelin sheath is made up of specialized cells called Schwann cells.

This sheath is not continuous, ie it does not surround the entire axon membrane; These uncovered spaces are known as Ranvier nodes.

it cools slower in the earth meaning the crystals have more time to form than lava on the surface

some of your causes might be acidic rain or natural wildfires that cause the parks to be degraded

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