Answer:
The muckrakers were reform-minded journalists in the Progressive Era in the United States (1890s–1920s) who exposed established institutions and leaders as corrupt. They typically had large audiences in popular magazines.
Explanation:
The slave trade from Africa to the America changed the world, undoubtedly.
The answer is letter C and B. Puerto Rican citizens do not vote for the president. They are US unincorporated territory and they are considered American citizens and are using the US Dollar as currency. Just like Guam, they can freely move to any any another place in the US.
The answer is A. both North and South Korea were run by a different government.