Final answer:
a) Jules Verne's personal diary. A potential primary source for David's essay on Jules Verne could be Jules Verne's personal diary.
Step-by-step explanation:
A potential primary source for David's essay on Jules Verne, the Father of Science Fiction, could be a) Jules Verne's personal diary. Diaries are written by the person themselves and provide firsthand accounts and insights into their thoughts, experiences, and creative process. Jules Verne's personal diary would offer valuable information about his life, ideas, and inspirations as a pioneer in the science fiction genre.