What U.S. principle is most likely to encourage grassroots political action?

The principle that most encourages grassroots political action is democracy. Democracy emphasizes the role of citizens in the political process, advocating for participation, representation, and the influence of the people in decision-making. Grassroots movements often arise from a democratic foundation, as they empower individuals and communities to organize, advocate for their interests, and drive change from the bottom up. This engagement is essential in a democracy, where the government is accountable to the will of the people.

In contrast, federalism refers to the division of power between national and state governments, which can sometimes complicate grassroots movements rather than encourage them. Judicial impartiality is about maintaining an unbiased judicial system, which does not directly promote citizen participation in political processes. Similarly, the separation of powers focuses on distributing authority among different branches of government to prevent any one branch from becoming too powerful, but it does not inherently boost grassroots political activity like democracy does.