Which of the following structures serves as the cell's boundary from its environment? mitochondrion chloroplast channel protein cell membrane

The cell membrane serves as the cell's boundary from its environment. It is a protective barrier that separates the cell from its surroundings and controls the movement of substances in and out of the cell. The cell membrane is selectively permeable, meaning it allows certain molecules to pass through while keeping others out. This selective permeability is essential for maintaining the cell's internal balance and regulating its interactions with the external environment.