Let's take a look at two real-world episodes in the market for gasoline and try to figure out why the price fluctuates so much.

a. In the spring of 2020, during the COVID-19 lockdown, the price of regular gasoline in the United States plummeted to $1.75 per gallon. Use the supply and demand model to determine which curve shifted and what happened to the equilibrium price of gasoline. For this part of the question, assume no other changes in the market for gasoline.

b. By the summer of 2021, the price of regular gasoline in the United States had bounced back and was hovering around $3.20 per gallon. Use the supply and demand model to determine which curve shifted and then what happened to the equilibrium price of gasoline. For this part of the question, assume no other changes in the market for gasoline.