The descriptions of the data models that come with the Splunk Common Information Model (CIM) Add-on are documented in the CIM Add-on manual (Option B). This manual provides detailed information about the data models, including their structure, the types of data they are designed to normalize, and how they can be used to facilitate cross-sourcing reporting and analysis.

The timechart command in Splunk requires the _time field to be present in the dataset because it uses time as the primary axis for charting data. The _time field represents the time of events and is essential for commands that generate visualizations based on time, such as timechart. This command groups the events into time intervals and performs statistical functions on those time intervals. Without the _time field, the timechart command will not function properly.
References:
Splunk Docs - timechart command

Reference: https://docs.splunk.com/Documentation/PCI/4.1.0/Install/PrivilegedUserActivity A tag is a descriptive label that you can apply to one or more fields or field values in your events1. You can use tags to simplify your searches by replacing long or complex field names or values with short and simple tags1. To search for events that contain a tag name, you can use the tag keyword followed by an equal sign and the tag name1. You can also use wildcards (*) to match partial tag names1. Therefore, option B is correct because it will return events that contain a tag name that starts with Pri. Options A and D are incorrect because they will only return events that contain an exact tag name match. Option C is incorrect because it will return events that contain a tag name that starts with Priv, not Privileged.

When defining a search macro, the required elements are the name and the definition of the macro. The name is a unique identifier for the macro that can be used to invoke it in other searches. The definition is the search string that the macro expands to when referenced. The arguments, validation expression, and validation error message are optional elements that can be used to customize the macro behavior and input validation2
1: Splunk Core Certified Power User Track, page 9. 2: Splunk Documentation, Define search macros in Settings.