Final answer:
Imposing an import quota on soybeans reduces the quantity of imported soybeans allowed beyond a certain threshold.
Step-by-step explanation:
When the United States imposes an import quota on imported soybeans, it reduces the quantity of imported soybeans allowed beyond a certain threshold. This means that there is a limit on the amount of soybeans that can be imported into the country. The quota sets a maximum quantity allowed, and any soybeans beyond that limit cannot be imported. This policy aims to protect domestic soybean producers and limit competition from foreign imports.