Which excerpt from "what the black man wants" best summarizes the speech?
i do not know, from what has been said, that there is any difference of opinion as to the duty of abolitionists, at the present moment.
how can we get up any difference at this point, or at any point, where we are so united, so agreed?
i am for the “immediate, unconditional, and universal” enfranchisement of the black man, in every state in the union.
shall we at this moment justify the deprivation of the negro of the right to vote, because some one else is deprived of that privilege?

At the time of the Reconstruction era, Mr. Frederick Douglass insisted that government’s actions require safeguarding land, rights to vote, as well as, national and communal impartiality for black Americans. “What the Black Man Wants” is the speech given by Douglass in April 1865. It was presented in front of an Anti-Slavery Society referred to as “Massachusetts Anti-SS”.

However, the last option in the query-"Shall we at this moment justify the deprivation of the Negro of the right to vote, because someone else is deprived of that privilege?"- presents the central idea of the disquisition or say, summarizes it.

the following key ideas correctly express the key sentence.

restate key idea: most people can learn to swim in ten short lessons.

restate key idea: the majority of water-accident victims require mouth-to-mouth breathing.

restate key idea: an empty, tightly closed gallon jug will support a tired swimmer.  

restate key idea: first aid is to prevent accidents as well as assist in rescue.

explanation: the key idea needs to have the same topic as the key sentence (drowning and safety).

idk but it looks like a week ago you posted this i hope you passed : )