Good luck i can't view the link, but I really hope you can get the answer
Neither is correct actually
The gaps (approximately 1 micrometer wide) formed between myelin sheath cells long the axons are called Nodes of Ranvier. Since fat serves as a good insulator, the myelin sheaths speed the rate of transmission of an electrical impulse along the axon.
Answer:
<em>The correct option is D) the natural extinction rate</em>
Explanation:
Extinction can be described as a process due to which species get removed from the world.
Background extinction can be described as the standard rate of extinction of organisms of a species due to ecological or environmental factors. It is a low-level type of extinction which occurs over a long period of time. It can be described as the natural extinction rate of individual organisms. Hence, option D best describes the natural phenomenon of background extinction.