Due to accidental oversupply in 2016, producers of butter (🧈) around the world produced substantially less butter in 2017. However, 2017 also saw massive changes in world demand for butter from both the United States and China.
In the US, fats became more accepted as "healthy" compared to sugars, so this change in
(income/complements/substitutes/tastes/expectations) caused Demand for butter to increase.
In China, workers received higher wages, so their increase in
(income/complements/substitutes/tastes/expectations) caused Demand for butter to increase.
As a result of these changes, the world price of butter
(increased/decreased) above the price in France (which we'll call "P*").
In most scenarios, the price inside France (P*) would just adjust to match the world price. But since French supermarkets tend to set the prices on their contracts ONCE a year, the price could not change to match the rest of the world.
As a result, P* in France was
than the world price, and so France experienced severe
(surpluses/shortages) of butter.