Which statement correctly distinguishes movement along the demand curve from a shift in the demand curve?

Which statement correctly distinguishes movement along the demand curve from a shift in the demand curve?

• A. Movement along is caused by a price change; a shift is caused by non-price determinants such as income.
• B. Movement along is caused by income; shift is caused by price change.
• C. Both are caused by price changes; no difference.
• D. Movement along changes the quantity supplied.

Answer: (A)

Movement along the demand curve happens when the price of the good changes. With all other determinants held constant, a lower price means more is bought (movement to the right), and a higher price means less is bought (movement to the left) along the same curve. A shift in the demand curve occurs when a non-price determinant changes. This changes the quantity demanded at every price, so the entire curve moves left or right. For example, higher income (for a normal good) increases demand at all prices, shifting the curve to the right; lower income or making the good inferior shifts it to the left. So the statement is correct because it separates price-driven movement along the curve from shifts caused by non-price factors like income. The other ideas misstate which variable drives movement or mix up demand with supply.

Movement along the demand curve happens when the price of the good changes. With all other determinants held constant, a lower price means more is bought (movement to the right), and a higher price means less is bought (movement to the left) along the same curve.

A shift in the demand curve occurs when a non-price determinant changes. This changes the quantity demanded at every price, so the entire curve moves left or right. For example, higher income (for a normal good) increases demand at all prices, shifting the curve to the right; lower income or making the good inferior shifts it to the left.

So the statement is correct because it separates price-driven movement along the curve from shifts caused by non-price factors like income. The other ideas misstate which variable drives movement or mix up demand with supply.