Which concrete detail is most relevant to Fredrick Douglass's autobiography?

One of the most relevant concrete details in Frederick Douglass's autobiography is his personal account of the physical abuse and violence he endured as a slave, as this highlights the harsh realities of slavery and the brutal treatment that slaves experienced. This detail helps to paint a vivid picture of the inhumanity and cruelty of the institution of slavery and adds credibility to Douglass's advocacy for abolition.