Question

some of these molecules keep the contents inside of the cell separated from the contents outside of the cell. others allow certain materials to be transported across the membrane. a few provide signals that can alter cell behavior, and some provide stability for the membrane. which molecule separates the contents inside of the cell from the contents outside of the cell? a carbohydrates b lipids c nucleic acids d protein

Explanation:

The cell - membrane is mainly composed of lipids which form a bilayer. This lipid bilayer serves as a barrier to separate the inside of the cell from the outside environment. Carbohydrates are often involved in cell - cell recognition and signaling, nucleic acids store genetic information, and proteins have various functions like transport and signaling but it is lipids that primarily separate the cell's internal and external contents.

Answer:

B. Lipids