Question: To set up Hadoop workflow with synchronization of data between jobs that process tasks both on disk and in memory, use the `___` service, which is `___`.
- Oozie; open source
 - Oozie; commercial software
 - Zookeeper; commercial software
 - Zookeeper; open source
 
Answer: The correct answer of the above question is Option D:Zookeeper; open source