I. It is a slow process
II. Molecules move in a random fashion, the net result being substances moving from regions of higher concentration to regions of lower concentration.
III. It is very important to plants since it is the only means for gaseous movement within the plant body.
IV. It is not dependent on a ‘living system’.
All these statements are correct for-

• A

  Simple diffusion

• B

  Facilitated diffusion

• C

  Active transport

• D

  Special type of facilitated transport