Which of the following conditions is essential for the inverse relationship between price and quantity demanded (Law of Demand) to hold true?

Consider the following statements regarding the dynamics of consumer demand: Statement 1: Expansion of demand is characterized by a downward movement along an existing demand curve resulting specifically from a decrease in the price of the commodity. Statement 2: An increase in demand is represented by a rightward shift of the entire demand curve driven by non-price factors such as rising consumer income or changing preferences. Which of the following options is correct?

According to economic theory, demand curves typically have a negative slope primarily because: