Why Did the number of African-Americans Who who participated in politics through voting and running for political office is almost completely disappear when the reconstruction era ended?

Because the African Americans who did show up to vote were told by white basically henchmen that their time to vote passed or that they were at the wrong polling venue and more or less basically the law may say u can vote but us backwards thinking white men say no so voting diminished because what's the point of showing up to vote just to be strong armed

explanation:

there are two statements that are incorrect.

1. the marshall plan was a lend lease program. it was an economic plan that europe redevelop itself after wwii.

2. einstein didn't really do anything to further the allied cause in building the bomb. he merely sent a letter to fdr telling him (in 1939) that if the united states entered the war, perhaps it would be wise to build the bomb before germany did. i would say this answer is incorrect, but when america entered the war 2 years later, fdr thought it might be a good idea to take einstein's advice.

the 4th choice is definitely so wrong that is likely the single answer of this question

montesquieu took the view that the roman republic had powers separated so that no one could usurp complete power. in the british constitutional system, montesquieu discerned a separation of powers among the monarch, parliament, and the courts of law.