This would be called a trade-of B.
The reason why this is correct is because if you can only build one thing as a company and you decide that building war equipment is more important to you, then you're doing a trade-off between building butter-making machines and army tanks.
Answer:
This will be my last answer for now, but I'm positive the Louisiana Purchase occured between France and the US during Jefferson's Presidency. It was a really good deal for the US, because it was a lot of land for little money. However, envoys under Jefferson negotiated the deal without his direct approval, meaning Jefferson was forced to push for ratification.