Which best describes dynamic equilibrium?

a. there is a difference in concentration on either side of the cell membrane.
b. there is an uneven distribution of particles inside and outside the cell.
c. particles are moving into and out of the cell, but their concentrations remain stable.
d. a concentration gradient is forcing water out of the cell and particles into the cell.

The correct option is C.
Cellular transport involves the movement of various particles across the plasma cell membrane. The transportation process can be active or passive. A dynamic equilibrium is said to be achieved in the cell when the water potential inside the cell is equal to that outside the cell. At this point, there is no net movement of water inside or outside the cell and the concentrations of particles move in and outside the cell remain constant.

"Particles are moving into and out of the cell, but their concentrations remain stable" is the one among the following choices given in the question that best describes dynamic equilibrium. The correct option among all the options that are given in the question is the third option or option "C". I hope it helps you.