A health campaign which claims that chocolate makes you fat
x
A rise in the price of chocolate substitutes
x
A fall in consumers' income
x
A demand curve shifts to the left when demand for the good at any given price level is less than before. Changes 2 and 4 both have this effect, although Change 4 applies to normal goods, not to inferior goods. Change 1 causes a movement along the existing demand curve. Change 3 causes a shift to the right of the demand curve.
