Final answer:
The option 'Preserve Illustrator editing capabilities' in the AI format ensures that Illustrator files maintain their layers, type, and other attributes for compatibility with other Adobe applications.
Step-by-step explanation:
When saving a file in the Adobe Illustrator (AI) format, the option that makes it possible for other Adobe applications to work with the file is c) Preserve Illustrator editing capabilities. This option ensures that layers, type, and other attributes within the Illustrator file are maintained in a way that can be interpreted by other Adobe software, like Photoshop or InDesign. While Embed fonts and Create outlines will help with text recognition and Flatten transparency will deal with transparency effects, preserving Illustrator editing capabilities is the option that generally keeps the file as editable and compatible as possible across different Adobe applications.