Which of the following best describes the arrangement of the main component of the plasma membrane?
a. A monolayer of phospholipids with the phosphate heads facing the cytosol and the fatty acid tails facing the extracellular fluid
b. A bilayer of phospholipids with the phosphate heads facing the cytosol and extracellular fluid, and the fatty acid tails facing one another
c. A bilayer of phospholipids with the phosphate heads of one layer facing the fatty acid tails of the other
d. A bilayer of phospholipids with a layer of triglycerides sandwiched in the middle