Your company is adopting BigQuery as their data warehouse platform. Your team has experienced Python developers. You need to recommend a fully-managed tool to build batch ETL processes that extract data from various source systems, transform the data using a variety of Google services, and load the transformed data into BigQuery. You want this tool to leverage your team's Python skills. What should you do?

A. Use Dataform with assertions. B. Deploy Cloud Data Fusion and included plugins. C. Use Cloud Composer with pre-built operators. D. Use Dataflow and pre-built templates.