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: The telegraph made communication much easier, the railroad made transportation of goods and people quicker and easier. The sewing machine made life on the plains easier.
What are the following countries...?
Assuming you're referring to Theodore Roosevelt, one of the most successful things he did in terms of regulating big business was the "break up the trusts,"--in that he took to court companies that were suspected of colluding with other firms and forming monopolies.
