What type of data contains both a defined schema and elements of variability, such as JSON and XML?

The correct choice focuses on semi-structured data, which is characterized by having a defined schema while also allowing for variability in the data content. This type of data provides both organization and flexibility. For instance, formats like JSON (JavaScript Object Notation) and XML (eXtensible Markup Language) comply with a set structure that can define relationships and data types but also permit the inclusion of diverse data elements and types. This combination means that semi-structured data can adapt to different needs without losing the inherent organization that enables it to be parsed and understood by machines.

In contrast, structured data adheres strictly to a predetermined model, such as databases with tables and defined data types, which does not offer the variability found in semi-structured formats. Unstructured data lacks any predefined structure, making it difficult to categorize and analyze, as seen with free text documents and multimedia content. Raw data refers to unprocessed data collected from various sources, which may still need to be transformed or organized before any meaningful analysis can occur. Therefore, the unique characteristic of semi-structured data is its balance between organization and flexibility, making it distinct from the other categories.