Explanation
Shadowing, interviewing, and leading workshops are three approaches that a consultant can use to learn about and empathize with the customer. Shadowing involves observing how the customer performs their tasks and interacts with their systems. Interviewing involves asking open-ended questions to understand the customer's goals, challenges, and pain points. Leading workshops involves facilitating group discussions and activities to elicit requirements, feedback, and solutions from the customer. Verified References:
https://developer.salesforce.com/resources2/certification-site/files/SGCertifiedSalesCloudConsultant.pdf (page 18)
https://trailhead.salesforce.com/en/content/learn/modules/consulting_skills_for_salesforce_professionals/d

Explanation
This is the recommended solution for Cloud Kicks if they want to search and cross-reference records with the original source database after migrating 70 million records from a legacy database to the data warehouse that will be synced with Salesforce. Using a custom External ID field and mapping it to the source record ID value will allow Cloud Kicks to uniquely identify each record and match it with its corresponding record in the source database. A custom External ID field is a custom field that has the External ID attribute enabled, which means that it can be used as a unique identifier for data import or integration purposes.