What is meant by "critical election" in the context of American politics?

A "critical election" refers specifically to an election that signifies a substantial shift in the political landscape, usually marked by a realignment of party loyalties. This type of election often indicates that the existing party system is undergoing significant changes, which can alter voter bases and lead to new political dynamics. For example, instances like the election of 1932, which brought Franklin D. Roosevelt and the Democrats to power during the Great Depression, showcase how critical elections can lead to a long-term shift in party dominance and voter allegiance.

In contrast, while high voter turnout and extensive media coverage can be important aspects of an election, they do not intrinsically signify a critical election. An election where the same party wins again may indicate stability rather than a transformative change in the political landscape, hence does not align with the concept of a critical election. Therefore, option B clearly encapsulates the essence of critical elections in American politics as events that reflect significant party realignment.