A decrease in the price of hot dogs will cause a movement from D2 to D1.
Step-by-step explanation:
The excess demand causes the price to rise and the quantity required to decrease. A decrease in demand and an increase in supply would cause an equilibrium price to decrease, but it can not determine the impact upon the equilibrium quantity.
You will also find that any change in the economy leads to a particular price change, mixture quantity :
Increase in demand: price rises; quantity falls.
Decreasing demand: decreasing prices, declining amount.
Increased supply: falling price, increasing quantity.