Which event from the 20th century best illustrates Alexis de Tocqueville's assertion that liberty was key to the United States' success as a constitutional republic?

A. The United States periodically granted certain nations preferential trading status.

B. The U.S. government exempted the Amish, who do not believe in government assistance, from paying social security taxes.

C. The Environmental Protection Agency was founded in 1970 to monitor and protect natural resources.

D. The United States was in the first group of nations to join the United Nations when it was founded in 1945.

Alexis de Tocqueville's concern for liberty had to do with personal liberties -- with freedom of conscience and belief being protected in a constitutional republic. By respecting the rights of the Amish to exempt themselves from the Social Security system, the government of the United States is allowing them to have liberty of their beliefs. They don't pay into the Social Security system, and also do not receive benefits from it. They choose to care for themselves and one another in the Amish community.

Alexis de Tocqueville's famous work was published in the 1830s. Based on his travels in the early United States, he wrote Democracy in America, in which he detailed how a democratic society functions.