Step 1: Understand the scenario.
A leftward shift in demand signifies a reduction in consumer purchasing at all price points, leading to a market imbalance.
Step 2: Sequence the events logically.
- (A) Demand decreases at any given price. → This is the initial consequence of the demand curve shifting left.
- (B) An excess supply situation arises. → With reduced demand, supply surpasses demand at the prevailing price.
- (C) Some producers will lower their prices. → Suppliers reduce prices to clear surplus inventory.
- (D) The new equilibrium involves lower quantity and price. → The market adjusts to a new equilibrium characterized by reduced price and quantity.
Step 3: Confirm the order.
The correct logical sequence is: (A) → (B) → (C) → (D).
Final Answer: \[\boxed{(A), (B), (C), (D)}\]