1 AU means 1 astronomical unit or the aproximate distance from the earth to the sun
1AU=<span>149597870.7 kiometers
1 billion=1,000,000,000
600 billion=600,000,000,000
</span>
<span>x times 1AU=600,000,000,000
x times </span>149597870.7=<span>600,000,000,000
solve for x
divide both sides by </span><span>149597870.7
</span>x=4010.75
so aprox 4011 AU's
They are thus known as the "supporting cells" of the nervous system. The four main functions of glial cells are: to surround neurons and hold them in place, to supply nutrients and oxygen to neurons, to insulate one neuron from another, and to destroy and remove the carcasses of dead neurons (clean up).
I’m pretty sure it’s B. Relative saying
The cell membrane allows substances to enter and leave the cell and gives the cell structure.
