In the first part of Benjamin Franklin's Autobiography, Franklin explains to his son some reasons why he starts writing the autobiography, please choose the reasons after you have a detailed reading of the excerpt.

A. He is interested in his family genealogy, that is, his family history.
B. He wants to instruct his posterity, the later generations of his family.
C. Through recording his life experience on paper, he can enjoy living his life again.
D. To gratify his vanity to make a success in his life both economically and socially from poverty to affluence and from obscurity to celebrity.