Your organization has data pipelines that require both batch and stream processing. The pipelines should be capable of integrating with machine learning models for predictive analytics. Which combination of GCP services should be used to design a scalable and flexible data pipeline?

*Explanation:* Cloud Dataflow with Cloud Pub/Sub and AI Platform is the correct choice for a scalable and flexible data pipeline that supports both batch and stream processing and integrates seamlessly with machine learning models. Cloud Dataflow can handle both batch and stream processing, Cloud Pub/Sub provides real-time data ingestion, and AI Platform supports machine learning model integration. The other options lack the necessary combination of services or are not optimized for this specific use case.