The correct choice is
"A", "The only Federal institution was Congress, and there was no president or national court system."
Congress was comprised of representatives picked by the states and could direct foreign affairs, influence bargains, proclaim war, keep up an armed force and a naval force, coin cash, and build up post offices.
Plant populations change over time by growing in size and diversity. They generally are the first part of an ecosystem after lichens (the pioneer species) and cause an ecosystem to flourish and allow for animals to move in. I don't know if this is the answer you were looking for but it should give you somewhat of a base.
A paper that talks about all of these topics could be titled "America's fear of communism, socialism, and anarchy after World War I."
All of the aforementioned events/people deal with fear felt by American citizens. For example, Sacco and Vanzetti were two Italian immigrants known for their political views. They believed in a society that had no government, also known as an anarchy. These two men were accused of, and later found guilty, of committing a murder. However, many individuals argued that they were found guilty not because of the evidence but rather the fact that they were anarchists.
The Palmer Raids were another result of fear towards a specific group. In this case, Attorney General Palmer raided the homes of 5,000 suspected communists. The goal was to uncover any plans to overthrow the American government. No evidence was found to support this conclusion.
