The cell membrane helps to control what enters and leaves a cell. The substance which accounts for two-thirds of a cells mass is water. That makes the answer D.
Nitrogen is not found in your body because i think its dangerous,at least liquid nitrogen is
Your answer would be C hope this helps friend ^^
A centrifuge helps you to <em><u>determine the volume of different components of </u></em><em><u>blood.</u></em>
Therefore, The option you marked is correct.
<em>Benjemin</em>