Which of the following has been the most important effect of the amendments added to the U. S. Constitution since the Civil War?

A. More people volunteer for military service.

B. More people are involved in the political process.

C. More people immigrate to the United States each year.

D. More people are eligible to run for president.

A) More people volunteer for military service.

A. More people volunteer for military service.

Explanation:

The 13th ended slavery forever in the United States, while the 14th made all persons born in the United States (including the former slaves) citizens of the nation and prohibited the states from denying anyone the privileges and immunities of American citizenship, due process or law, or equal protection of the law. Finally, the 15th Amendment, ratified in 1870, prohibited the states from denying the franchise to anyone based on "race, color, or previous condition of servitude."

When the war began, federal law denied African-Americans virtually all constitutional rights. In Dred Scott v. Sandford, decided in 1857, Chief Justice Roger B. Taney ruled that blacks could never be citizens of the United States, even if they were treated as citizens in the states where they lived. This led to the oddity that blacks could vote for members of Congress and presidential electors in six states, and could hold office in those states and some others, but they were not citizens of the nation. Federal law nevertheless supported Taney's rulings. For example, before the war blacks could not be members of state militias, serve in the national army, receive passports from the State Department, or be letter carriers for the post office.