You cannot substitute the Extract process with another data manipulation process such as the Select or Audience process. The Extract process allows you to retrieve only those optimized transactions that are needed from Contact Optimization that you submitted into the Contact Optimization session. These transactions are typically scoped by campaign, flowchart, and Optimize process, and possibly by other criteria such as channel or date. Another data manipulation process would retrieve by Audience IDs, incorrectly including optimized transactions that have nothing to do with a particular campaign. That is, surviving contact transactions to the same individuals submitted by another campaign.