As a professional working for a public transportation company, you are tasked with building a predictive model to estimate delay times for various routes. These predictions will be delivered to users in real-time via an app, and the model requires monthly retraining to account for seasonal and population changes. The solution must be cost-effective, scalable, and comply with data privacy regulations. According to Google's recommended best practices, which of the following options provides the BEST end-to-end architecture for this model? Choose the best option.