Final answer:
The plasma membrane consists of a double layer of phospholipid molecules with embedded proteins and surface carbohydrates, known as a phospholipid bilayer. Therefore correct option is B
Step-by-step explanation:
The correct option for the composition of the plasma membrane is B) a double layer of phospholipid molecules in which proteins are embedded. The plasma membrane is often described by the fluid mosaic model, which highlights the dynamic nature of the membrane's structure. This structure is characterized by a phospholipid bilayer with hydrophilic heads facing outwards towards the water-based environments inside and outside the cell, and hydrophobic tails facing inwards away from the water.
Embedded within this bilayer are various proteins that can either span the entire membrane or are attached on one side. Additionally, carbohydrates are attached to proteins (forming glycoproteins) or lipids (forming glycolipids) on the cell's exterior surface. The presence of cholesterol in the membrane helps with fluidity and stability.