You are developing a globally scaled frontend for a legacy streaming backend data API. This API expects events in strict chronological order with no repeat data...

You are developing a globally scaled frontend for a legacy streaming backend data API. This API expects events in strict chronological order with no repeat data for proper processing.
Which products should you deploy to ensure guaranteed-once FIFO (first-in, first-out) delivery of data?

A. Cloud Pub/Sub alone B. Cloud Pub/Sub to Cloud Dataflow C. Cloud Pub/Sub to Stackdriver D. Cloud Pub/Sub to Cloud SQL