Final answer:
D) Manuscripts. The most important note for a report about Sir Arthur Conan Doyle's writing career is manuscripts
Step-by-step explanation:
In a report about Sir Arthur Conan Doyle's writing career, the most important note from the options given would be manuscripts. Manuscripts are the original handwritten or typed copies of an author's work and they provide valuable insights into the author's writing process, style, and creative ideas. They are often studied by literary scholars and enthusiasts to understand the evolution of an author's works and their impact on the literary world.