Which data stream allows you to collect data from an iOS application in Google Analytics 4?

The correct answer is App data stream, which is specifically designed to collect data from mobile applications, including iOS applications. In Google Analytics 4, data streams are categorized based on the source of the data, and the App data stream facilitates the tracking of user interactions and events that occur within mobile apps.

When setting up an App data stream, you can receive information such as user engagement metrics, app screens viewed, and in-app events, all of which are critical for understanding user behavior within a mobile environment. This data stream is tailored to utilize mobile-specific capabilities and integrate seamlessly with the unique structure of app data collection.

In contrast, the other options do not pertain to iOS app data collection. The Web data stream is intended for gathering data from websites, the User data stream is not a recognized category within GA4, and the Conversion data stream generally involves tracking specific actions defined as conversions, rather than serving as a distinct mechanism for gathering data from a mobile app. This distinction reinforces why the App data stream is the appropriate choice for capturing iOS application data.