Final answer:
The consultant should recommend using Data Filters or Query Activities to create a Sendable Salesforce Data Extension for the email campaign and Data Stream to sync Sales Cloud objects to the Marketing Cloud.
Step-by-step explanation:
To recommend an approach for filtering a subset of a Synchronized Data Extension based on custom object data and returning tracking to the Sales Cloud, one must understand the capabilities of Salesforce Marketing Cloud (SFMC). The consultant should recommend using Data Filters or Query Activities to create a Sendable Salesforce Data Extension that will be used for the email send.
Data Stream: This will automatically sync Sales Cloud objects, such as the custom object data mentioned, into Marketing Cloud.
Data Filters or Query Activities: These can be used to segment the synchronized data and output a Sendable Data Extension specific to the targeted subset. Data Filters offer a user-friendly interface for segmentation, while Query Activities allow for more complex queries using SQL.