In most mammalian cells, how does glucose typically enter the cell across the plasma membrane under normal physiological conditions?

• A. By vesicular uptake through clathrin-mediated endocytosis as the main mechanism
• B. By facilitated diffusion through GLUT transporters down its concentration gradient
• C. By simple diffusion through the lipid bilayer because glucose is nonpolar
• D. By primary active transport via the ${\mathrm{Na}}_{+}$/$K_{+}$-ATPase directly pumping glucose into the cytosol

Answer: (B)