Final answer:
The most obvious revolution of Reconstruction was the election of hundreds of black politicians to office, marking a significant change in political representation and contributing to the transformation of American governance.
Step-by-step explanation:
One of the most obvious revolutions of Reconstruction was C. Hundreds of black politicians were elected to office. This era marked a significant turn where for the first time, freed African Americans began to enter the political arena, taking on roles that had been previously unattainable due to the institution of slavery and systemic racial barriers. The shift towards black political representation was a stark change from the pre-Civil War status quo and represented a glimpse of the social transformation that Reconstruction sought to achieve.
Despite President Andrew Johnson's intention for a lenient approach to Reconstruction that included his Proclamation of Amnesty and Reconstruction, and the nomination of provisional governors to lead the formation of new state constitutions, the most radical change was the involvement of African Americans in politics.
This occurred amidst significant resistance and backlash, as well as varied successes and failures in safeguarding civil rights and ensuring effective governance. Nevertheless, the entry of hundreds of black politicians into office during Reconstruction was one of the era's most unmistakable signs of a shifting American political landscape.