Fields extracted with the Field Extractor are specific to what:

Fields extracted using the Field Extractor are associated with the host, source, or source type of the data. This means that when fields are created through the Field Extractor, they are defined based on the characteristics and context of the incoming data from the specific source, such as log files from a particular application, the type of data being processed, or the source itself.

This functionality allows for a flexible and dynamic approach to field extraction, enabling users to tailor the extracted fields to the specific structure of their data. For instance, when working with different log formats from various applications, fields can be extracted according to the conventions of those formats, allowing users to efficiently analyze and visualize the data.

In contrast, while user accounts, applications, and operating systems may be relevant to data management and usage in Splunk, the main focus of the Field Extractor is on the data context tied to host, source, or source type. Therefore, the correct choice reflects the specific relationship between field extraction and the nature of the data being processed.