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Your team is developing a global banking application aimed at serving millions of users worldwide. The application features a sophisticated forecasting model designed to predict individual account balances three days in advance. These predictions will be used to trigger personalized notifications for users whose account balances are forecasted to fall below $25. Given the scale of the application and the need for real-time, efficient, and scalable notification delivery, what is the most effective method to serve these predictions? Consider factors such as scalability, cost-effectiveness, and the ability to deliver personalized notifications in real-time. Choose the best option from the following:
A
Implement a custom notification system using Firebase, where each user is registered with a unique user ID on the Firebase Cloud Messaging server. Notifications are sent based on the average prediction of all account balances falling below the $25 threshold, rather than individual predictions.
B
Create a dedicated Pub/Sub topic for each user and deploy a Cloud Function that triggers a notification whenever the model predicts that a specific user's account balance will drop below the $25 threshold.
C
For each user, establish a Pub/Sub topic and deploy an application on the App Engine standard environment that sends a notification when the model predicts that the user's account balance will drop below the $25 threshold.
D
Leverage Firebase Cloud Messaging (FCM) by building a notification system where each user is registered with a unique user ID. Notifications are sent individually based on the model's prediction that a specific user's account balance will drop below the $25 threshold.
E
Combine the use of Firebase Cloud Messaging for notification delivery with Pub/Sub topics for each user to ensure scalability and real-time processing. Notifications are sent based on individual predictions.