- Data import
- HTTP request
- Modify event
- Measurement Protocol
The correct answer is: Measurement Protocol
If you have been collecting data on your point-of-sale system and you send that data to Google Analytics from your website and app. Measurement Protocol allows you to collect and send events directly to Google Analytics servers.
Measurement protocol is a standard set of rules for collecting and sending events directly to Google Analytics servers. Measurement Protocol lets you send data to Analytics from internet-connected devices like a kiosk or point-of-sale system that complement your website or app.
Read more here: https://support.google.com/analytics/answer/9900444