Final answer:
Anna should insert a comment directly into the document to communicate with her collaborator, as it allows for specific, contextual, and efficient feedback.
Step-by-step explanation:
The best way for Anna to communicate with her collaborator about a specific paragraph in a document is to insert a comment. This can be done by highlighting the desired text and clicking New Comment in the tools ribbon to create a comment box in the margin, where she can type her message. This method is precise and allows the collaborator to see the comment in context. Alternatively, Track Changes could be used if Anna is specifically suggesting revisions to the text, but for general communication leaving a comment is typically more appropriate.
If Anna's message is very complex or sensitive, or if the context requires a more extensive discussion, sending an email or speaking in person might be better. However, for quick notes or feedback directly related to specific content in a document, comments are efficient and effective.
In summary, Anna should use the commenting feature of her word processing software to leave a message for her collaborator, ensuring specificity and clarity in her communication.