Final answer:
The price of a gallon of milk changes primarily due to B. inflation, which can be caused by too many dollars chasing too few goods, particularly after periods of war or during peacetime when price controls are lifted.
Step-by-step explanation:
The question is asking about the cause of changes in the price of a gallon of milk over time. B. Inflation is a significant factor that affects the price of goods, including milk.
We can describe the cause of inflation as an economic situation where there are too many dollars chasing too few goods.
For instance, government spending increases significantly during times of war, while consumer goods may be scarce since production focuses on the war effort.
After wars, price controls are typically lifted, leading to a surge in buying power and subsequently, inflation. Conversely, when there are too few dollars in circulation relative to available goods, it could result in deflation, especially during economic slowdowns like recessions or depressions.