What accurately describes diffusion?

Diffusion is best described as the passive movement of molecules from an area of high concentration to an area of low concentration. This process occurs because molecules are constantly moving and colliding with each other, leading to a net movement in the direction that results in equal distribution. This concept aligns with the principles of entropy, where systems tend to move toward a state of greater disorder or equilibrium.

The term "passive" is important because it indicates that diffusion does not require energy input; it happens naturally due to the kinetic energy of the molecules involved. This distinguishes diffusion from other forms of transport, such as active transport, which requires energy to move substances against their concentration gradient.

Other options describe processes that either do not align with the principles of diffusion or misrepresent the characteristics of diffusion. Therefore, the correct choice accurately captures the essential nature of diffusion in biological systems.