Biology

The correct answer is: B.Phospholipid bilayer, transport proteins, carbohydrates, and cholesterol.

These are the four main components of the cell membrane:

1.Phospholipid bilayer: The fundamental structure of the membrane, made up of two layers of phospholipids. The hydrophilic (water-attracting) heads face outward, while the hydrophobic (water-repelling) tails face inward, creating a semi-permeable barrier.

2.Transport proteins: These proteins span the membrane and help facilitate the movement of substances (ions, nutrients, etc.) into and out of the cell. Some transport proteins act as channels, while others are carriers or pumps that require energy.

3.Carbohydrates: These are often attached to proteins (glycoproteins) or lipids (glycolipids) and play key roles in cell recognition, signaling, and interactions with other cells.