Explain how each of the following illustrates one of the three principles of economy-wide interactions.

a. The price of solar panels has fallen by nearly 99% over the past 40 years. Prices are projected to continue falling over the next 30 years.

b. The financial crisis of 2008 caused unemployment to soar. In response, the White House urged Congress to pass a package of temporary spending increases and tax cuts early in 2009.

c. With oil prices plummeting, Canadian and U.S. oil companies have been forced to shut down their productive wells. In cities throughout North Dakota, Wyoming, Texas, and Alaska, restaurants and other consumer businesses are failing.