What Is the Main Function of Myelin

What is the main function of myelin?

A) To connect the end of an axon to the terminal buttons.
B) Myelin consists of a bilayer of continuous sheets of phospholipids that separate two fluid environments.
C) To pass information from the axon across the synapse in the form of a neurochemical message.
D) Myelin speeds the rate of information transfer in neurons and ensures that the message gets to the end of the axon.
E) None of the above is a function of myelin.