Which process is characterized by the movement of particles from an area of high concentration to an area of low concentration across the plasma membrane without the use of energy?
osmosis
active transport
passive transport
dynamic equilibrium

Its passive transport.

Explanation:

Transport can be wither passive transport or active transport. The terms passive and active are with respect to the usage of energy. If energy is required we call it as active process, if energy is not needed we call it as passive process. We know that particles always move from higher concentration to lower concentration and for this energy is not required, thus it is called passive transport. We can also refer it as movement of particles along the concentration gradient.

If the particles move against the concentration gradient i.e. from lower to higher concentration, then energy is required in the form of ATP. Such process is called active transport.

Osmosis is with respect to the movement of water (solvent) across the membrane. Water moves towards higher solute concentration from a region of lower solute concentration.