The diagram below shows the supply curve (SSS) and the demand curves (D1 D_1\,D1 and D2D_2D2) in the market for a consumer good. The initial market equilibrium is at E1E_1E1.

A fall in consumer incomes causes demand to decrease from D1 D_1\,D1 to D2D_2D2, resulting in a new market equilibrium at E2E_2E2. The market mechanism that leads to the establishment of the new equilibrium is initiated by
excess demand for the good at the initial price of P1P_1P1.
excess supply of the good at the new price of P2P_2P2.
excess supply of the good at the initial price of P1P_1P1.
excess demand for the good at the new price of P2P_2P2.