Option 4: (B), (D), (A), (C) -> When the price of Good Y (a substitute) decreases, the logical sequence is: First, the consumer realizes that Good Y has become relatively cheaper than Good X (B). This prompts the consumer to shift consumption from Good X to Good Y (D). As consumers shift away, the demand for Good X decreases (A). Finally, this decrease in demand is represented graphically as a leftward shift of the demand curve for Good X (C). This sequence follows the cause-and-effect relationship in consumer behavior when prices of substitute goods change. -> correct