the plasma membrane a. is rigid and impermeable b. is free of proteins c. is permeable to ions and polar molecules d. is composed mostly of cholesterol e. controls the contents of the cell

bilayer

Explanation:

The plasma membrane is SEMIpermeable, it can allow certain materials like nonpolar molecules to pass though its membrane so choice A is wrong. Choice B is also wrong because the plasma membrane is a phospholipd bilayer, meaning it has proteins. Choce C isn't correct  because cholesterol is not composing most of the membrane.

Choice E is your best answer because the most important function of the plasma membrane is to control what enters and exits the cell.

Hope this helps and makes sense to you! Good luck.

when the displaced particles are perpendicular to the direction the wave travels, is called a transverse wave, whereas in longitudinal wave the displace practices are parallel to the direction of the wave.

in the given image:

first image shows - longitudinal wave

second image shows - transverse wave

third image shows - longitudinal wave

fourth image shows - longitudinal wave