The law of demand states that, ceteris paribus, as price falls, quantity demanded:

• A. Rises, along the demand curve (movement along).
• B. Falls, along the demand curve.
• C. Shifts left.
• D. Remains unchanged.

Answer: (A)

The main idea is the law of demand: price and quantity demanded move in opposite directions when all other factors are held constant. When price falls, the quantity demanded rises because the lower price makes the good more affordable, so consumers buy more. This change occurs as a movement along the existing demand curve, not a shift of the curve itself, since the curve would only shift if non-price determinants (like income, tastes, or prices of related goods) changed. The rise in quantity demanded with a lower price is also helped by the substitution effect (the good becomes cheaper relative to alternatives) and the income effect (buyers feel richer as purchasing power increases). Hence, the statement that quantity demanded rises along the demand curve as price falls is the correct description. The other possibilities describe the curve shifting or no change, which doesn’t align with the law of demand under ceteris paribus.