It is the "National Labor Relations Board" that acts as a mediator in disputes between unions and employers, since many people on both sides of the dispute often claim that the other side is acting unjustly, especially when it comes to negotiations.
The correct answer is either A. OR D.
Using simple words, imperialism is a policy of certain country involving a will of extending its power by using any kind of pressure or force.
For example - In 1939 Nazi Germany together with Soviet Russia jointly invaded Poland, in the result, both countries extended its borders.
