Answer: Dickens drew on his own experience while writing it.
Explanation:
An autobiography is a text that is based on the life of the author which means that it was written by them about themselves.
If "David Copperfield" is Charles Dickens's most autobiographical book then it means that this book contains the most information about Dickens's actual life than any other book which essentially means that he drew on his own experiences in writing this book.
