Final answer:
A true statement about the Democratic and Republican parties is that they historically gravitate towards moderate positions, though they've become more polarized since the 1990s. Both parties uphold foundational American values and participate in the democratic process, even as they increasingly diverge on specific policy stances.
Step-by-step explanation:
The true statement about the Democrats and Republican parties is that both parties tend to gravitate towards more moderate positions, as the two-party system in the United States encourages a level of "ambiguity" in policy alternatives. This means that political parties are not as prone to back highly controversial issues that could harm their candidate's chances of election.
However, since the 1980s and especially in the 1990s, there has been an increase in political polarization with the moderate members of each party disappearing and ideologically driven candidates becoming more common. As a result, the Democrats in Congress have become more liberal, and the Republicans more conservative. The clear distinction between party positions can be viewed as advantageous since it provides voters with distinct choices, even though it also signifies the end of an era where bipartisan cooperation was more common.
Both the Democratic and Republican parties hold core American values such as liberty, equality, and individualism. They operate within the framework of the Constitution and the democratic electoral process. Differences arise, however, on specific policy issues and the general political ideology each party advocates, with Democrats leaning more liberal and Republicans more conservative.