When a demand curve shifts to the left, it indicates a decline in consumer purchasing power or preference for a product at every price level. This economic event triggers a series of adjustments in the market. Let's examine the sequential order of the statements provided to understand these market dynamics.

Demand Curve Leftward Shift: Initial Market Signal

The first consequence observed following a leftward shift in the demand curve is often an imbalance at the previous equilibrium price. When demand decreases, the quantity consumers are willing to buy falls. If the price remains at its prior level, the quantity supplied will exceed the quantity demanded, leading to:

(B) Excess supply will be there.

This surplus occurs because the market price has not yet adjusted to the new, lower level of demand. Producers find they have more inventory than they can sell at the current price.

Demand Curve Leftward Shift: Confirmation of Reduced Demand

Following the observation of excess supply, a clearer understanding of the situation emerges. The core nature of the leftward demand shift is that demand has fallen across all price points. This confirmation is represented by:

(A) At any given price, demand is less.

This statement reiterates the fundamental characteristic of the demand shift that caused the excess supply. It clarifies that the issue is a pervasive reduction in willingness to buy, not just an anomaly at a single price.

Demand Curve Leftward Shift: Producer Response

Faced with excess supply (B) and the confirmed reduction in demand (A), producers must act to restore market balance and avoid holding unsold inventory indefinitely. Their typical response is to:

(C) Some producers will decrease the prices of commodity.

Lowering prices makes the product more attractive to consumers, encouraging them to purchase more goods. This action aims to clear existing stock and align sales with the reduced demand.

Demand Curve Leftward Shift: Reaching a New Equilibrium

As producers implement price reductions (C), the market moves towards a new state of balance. Lower prices stimulate buying and discourage some production, leading to the establishment of a new equilibrium:

(D) At new equilibrium, quantity and price will be less.

In this new equilibrium, both the market price and the total quantity of the good traded will be lower than before the demand curve shifted leftward. This outcome reflects the decreased overall desire for the product in the market.

Thus, the correct sequential order in which these statements describe the process following a leftward shift in the demand curve is (B), (A), (C), (D).