Your chemical company needs to manually check documentation for customer order. You use a pull subscription in Pub/Sub so that sales agents get details from the order. You must ensure that you do not process orders twice with different sales agents and that you do not add more complexity to this workflow. What should you do?

A. Use a Deduplicate PTransform in Dataflow before sending the messages to the sales agents. B. Create a transactional database that monitors the pending messages. C. Use Pub/Sub exactly-once delivery in your pull subscription. D. Create a new Pub/Sub push subscription to monitor the orders processed in the agent's system.