The correct statement about the Peoria Speech is:
A. Lincoln suggested that freed slaves might be sent to Africa.
While Lincoln did express concerns regarding the future of slavery and the idea of colonization, particularly the idea that freed slaves could be relocated to other areas, the most notable aspect of his Peoria Speech is its opposition to slavery and its expansion. Therefore, the statement that matches the content of the Peoria Speech is A. However, B is misleading as Lincoln did not explicitly use that phrase.
If we're looking for the most accurate statement that aligns with the themes of the speech, it would be A, despite its historical context.
D refers to the fact that Lincoln was indeed responding to arguments from Douglas, but the specifics of that may not align directly with the main themes of the speech.
While you might find debates regarding slavery and freedom in the speech, the direct statement aligning with the Peoria Speech overall context best fits with A regarding colonization.