The main difference between active and passive transport across the cell membrane is:

• A
  Passive transport is non-selective whereas active transport is selective.
• B
  Passive transport requires a concentration gradient across a biological membrane,whereas active transport requires energy to move solutes.
• C
  Passive transport is confined to anionic carrier proteins,whereas active transport is confined to cationic channel proteins.
• D
  Active transport occurs more rapidly than passive transport.