Which statement below best describes the political party changes of the mid-1800s? A. a new Whig party formed
B. The republican party grew
C. The democrat party grew
D. Most of the United States supported slavery

The correct answer is B. The republican party grew.

Explanation

During the mid-nineteenth century, the policy of the United States was changed because during this time it was the end of the Civil War in which the Union achieved victory on April 9, 1865, over the Confederation. This meant including changes in the laws including three amendments to guarantee the freedom of the nearly four million African Americans who had been slaves, making them citizens and giving them the right to vote. This had consequences because the Democrats party's supporters were mainly in the Southern States (Confederate), and they had to accept the measures that the Republican majority congress imposed to reunify the country. Therefore, the Democratic party could not participate in some elections while the Republican Party was strengthened. So the correct answer is B. The republican party grew.