In his memoir, Sampson Davis describes the experience of growing up in Newark. He tells us that he came from an impoverished background, and that he faced enormous difficulties and obstacles in order to become a doctor. However, even after he became a doctor, Davis believed it was important for him to come back and become a beacon of hope for other people who had grown up in the same difficult environment. He wanted to come back and show young people that it was possible for them to change their lives through education.
You can tell when he works he is messy, which sets him up as a messy worker, with possible mistakes. It shows that the reason he is messy is that he is focused.
This is what I got from this.
'Finally' is the answer the others don't make sense if you try to read them with the rest of the sentence.