You are designing a basket abandonment system for an ecommerce company. The system will send a message to a user based on these rules:
- No interaction by the user on the site for 1 hour
- Has added more than $30 worth of products to the basket
- Has not completed a transaction
You use Google Cloud Dataflow to process the data and decide if a message should be sent. How should you design the pipeline?

A. Use a fixed-time window with a duration of 60 minutes. B. Use a sliding time window with a duration of 60 minutes. C. Use a session window with a gap time duration of 60 minutes. D. Use a global window with a time based trigger with a delay of 60 minutes.