How can users identify if a question is not compatible with the offline app?

Users can identify if a question is not compatible with the offline app by looking for a red square icon to the left of the question. This visual cue indicates an incompatibility, making it easy for users to spot issues at a glance. The red square acts as a clear alert, directing users to review and possibly modify the question to ensure it meets the requirements for offline functionality.

In contrast, the other options suggest alternative identification methods that may not provide the same level of immediate visual feedback. While a warning message could potentially inform users about incompatibility, it may not be as easily noticed as the red icon during survey design. Similarly, the inability to edit a question in the offline app or it being greyed out might cause confusion, as these conditions could arise for various reasons unrelated to compatibility. The red square provides a straightforward and intuitive way to identify problematic questions at a glance.