It would appear that he was very secretive of his work , it was even thought that da vinci wrote his work backwards that way it would become harder to read . It would be d . strictly for his own use .
I am not sure but I think the answer might be B: (light meter, aperture, exposure) because they can either photoshop and or use different filters and edit with certain apps.
Pretend you’re already asleep, keep your eyes closed, breathing steady, and avoid fidgeting.