You are a data engineer working on optimizing a large dataset stored in Delta Lake to improve query performance for analytical workloads. The dataset contains sales transactions with columns including 'date', 'region', 'user_id', 'product_id', and 'amount'. The queries frequently filter on 'date' and 'region', and often perform equality lookups on 'user_id'. Given the need to minimize query latency while considering cost and scalability, which of the following indexing and partitioning strategies would you implement? Choose the best option._