Which type of data source connects two different contact data tables to each other based on a particular field?

The correct answer involves understanding the function of an Attribute Group in Salesforce Marketing Cloud's Data Designer. An Attribute Group is used to connect multiple data extensions and relates different contact data tables based on common fields or attributes. This allows marketers to build a relational data model where different data sources can be linked together, providing a more comprehensive view of customer data.

Attribute Groups facilitate the organization and understanding of relationships between various pieces of information, making it easier to perform targeted marketing campaigns by utilizing these relational connections. This enables marketers to create segmentation and audiences based on a combination of attributes present in different tables.

In contrast, while Synchronized Data Extensions relate to the process of bringing in data from external sources, they do not specifically connect different data tables together based on fields. A Population is typically used for identifying specific groups of contacts within a contact model and does not reference connecting data tables. Data Designer itself is a tool that helps in creating and managing data models but does not refer to the specific act of connecting tables based on fields; rather, it's the framework that allows for the creation of these relationships through Attribute Groups.