Final answer:
The principal force in diffusion is passive transport, where particles move from an area with higher concentration to one with lower concentration without the use of energy.
Correct option is d) Passive transport
Step-by-step explanation:
The principal force driving movement in diffusion is the movement of particles from an area of higher concentration to an area of lower concentration, which is a process known as passive transport. While osmosis specifically refers to the diffusion of water across a membrane, facilitated diffusion involves the use of carrier proteins to move substances across a membrane and is also driven by the concentration gradient. Active transport, on the other hand, moves substances against the concentration gradient and requires energy, typically in the form of ATP.
Diffusion is a passive transport process that involves the movement of particles from an area of higher concentration to an area of lower concentration. It does not require energy input and is driven by the natural tendency of particles to move down their concentration gradient.