Why do cells have a plasma membrane? A.) to separate proteins from the nucleus
B.) to define the size of the cell
C.) to distinguish plants from animals
D.) to separate the inside of the cell from its environment

D.  to separate the inside of the cell from its environment

Explanation:

The cell membrane is primarily made up of lipids and proteins. It provides protection to the cell by keeping the interior of the cell separated from its external environment.  

It is a selectively permeable membrane meaning that it only allows certain substances to pass through it. It is involved in various cellular processes like cell signaling, cell adhesion, endocytosis, exocytosis etc.

hello there the answer is d

image result for how many calories of energy will 20 grams of carbohydrates provide in one gram provides 4 calories

consuming the right balance of protein, carbohydrates and fat can you maintain a healthy weight and optimize your energy levels. protein and carbohydrates both contain 4 calories per gram, while fat provides 9 calories per gram.