You are tasked with developing a machine learning solution for a retail company that wants to predict customer churn based on historical transaction data stored in BigQuery. The solution must support exploratory data analysis, feature selection, model building, training, hyperparameter tuning, and serving, all without requiring manual coding. The company emphasizes the importance of scalability, cost-efficiency, and the ability to repeat the classification process across multiple datasets with minimal setup. Given these requirements, which of the following approaches is the most efficient? Choose the best option.