Question

for diffusion to occur, which condition must be met?
a concentration gradient must exist.
a hypotonic external environment must exist.
a hypertonic external environment must exist.
dynamic equilibrium must exist.

Explanation:

Diffusion is the movement of substances from an area of higher concentration to an area of lower concentration. A concentration gradient, which is the difference in concentration between two regions, is essential for this movement to occur. Hypotonic or hypertonic environments relate more to osmosis in the context of cells and water movement, and dynamic equilibrium is a state that can be reached after diffusion has occurred, not a requirement for it to start.

Answer:

A. A concentration gradient must exist.