The two-party system in the United States has exhibited which of the following features:

A  It has remained unchanged since the early 1800s with the Democratic and Republican parties representing the same regions, constituencies, and political values.

B  It has evolved over time with the Democratic and Republican parties at times changing some of their core values and ideologies.

C  The two-party system operates under the principle of shared power in which third and fourth party candidates form coalition governments in conjunction with the Democratic and Republican parties.

D  Both the Democratic and Republican parties have become more liberal over time with the Democrats abandoning their pro-slavery stance and the Republicans pushing for increased government funding of a wide variety of public assistance programs.