Which diagram best explains a cause and effect relationship that has shaped u. s. politics?

The correct answer is "C)":

The origins of the 2 main political parties in the country: The Republican Party and the Democrat party, come from the 19th century and the rivalry between them has been going on since.

The Republican Party or Grand Old Party was founded in 1854. It stood against the extension of slavery to the country´s new territories and aimed for the complete abolition of slavery as well as the minimum interference by the government in economic affairs. Their current view is American conservationism.

The Democratic Party was founded in 1828. It initially supported slavery and opposed to civil rights reforms during the 19th century. However, it had a major change in its ideology during the 20th century, as it shifted to the support of organized labor and the civil rights of minority populations. Their current view supports modern Liberalism which promotes social and economic equality.

More than 150 years of rivalry and tradition have contributed to this prevalence of the two-party system in the United States.

the 4th option is the answer