Which characteristic makes a cell membrane selectively permeable? the smooth outside of the membrane the chemical nature of the membrane the rigid nature of the membrane the thickness of the membrane

The inside or outside

chemical nature of the membrane

Explanation:

The cell membrane is bilayer of amphipathic phospholipids and proteins The hydrophobic tails of phospholipids make the inner core of the membrane while hydrophilic heads are oriented towards the surface of the membrane.

The membrane is selectively permeable as it allows only nonpolar, small and uncharged substances to pass through its hydrophobic inner core. Hence, the chemical nature of the membrane makes it choose the allowed substances to be transported.