The cell membrane is selectively permeable, meaning it allows certain substances to pass through while preventing others from entering or exiting the cell. This selectivity is crucial for maintaining a stable internal environment within the cell.

Option 1 states that the cell membrane is made up of selected organic molecules, which is not entirely accurate. While it is true that the cell membrane is composed of organic molecules such as lipids and proteins, this alone does not explain its selective permeability.

Option 2 states that the cell membrane does not allow the transport of some substances from an area of higher concentration to an area of lower concentration. This is incorrect because the cell membrane can allow the movement of substances both with and against their concentration gradient. The movement of substances from an area of higher concentration to an area of lower concentration is known as passive transport.

Option 3 states that the movement of organic molecules occurs only at specific concentrations. This is not accurate because the cell membrane can regulate the movement of various molecules, not just organic ones, regardless of their concentration.

Option 4 is the correct answer. The cell membrane permits the movement of certain molecules in and out of the cell through various mechanisms such as diffusion, facilitated diffusion, and active transport. At the same time, it prevents the passage of other molecules