Answer:
The correct answer is b the magnitude of the concentration gradient of the molecule.
Step-by-step explanation:
Dffusion is one of most important membrane transport process that allow several molecules such as gases oxygen and carbon dioxide to pass directly across the plasma membrane.The is no involvement of carrier proteins or ion channels during passive diffusion.
During passive diffusion molecules are transported along their concentration gradient that means from the region of high concentration to region of low concentration,until the concentration of both regions become same.