Tags can be searched with tag=<tagname> and Boolean operators.
Extract: "Use tag=<tagname> to search for events with that tag. Use Boolean operators such as NOT to exclude tags." Therefore, tag=Marketing NOT (tag=San_Francisco) correctly filters Marketing-tagged employees excluding those tagged San_Francisco.

https://docs.splunk.com/Documentation/DashApp/0.9.0/DashApp/chartsBub

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 fillnull command replaces null or missing values in specified fields with a given replacement value. In this example, the command sets the src field to "Unknown" wherever it is null. It does not affect other fields or convert values from "Unknown" back to null.
Reference:
Splunk Power User Study Guide, Search Commands Section
Splunk Docs: fillnull Command
"fillnull replaces null field values with a specified string or number for a given field or fields."

The correct answer is C. Creates reports without using SPL. This is because the Pivot tool is a feature of Splunk that allows you to report on a specific data set without using the Splunk Search Processing Language (SPL). You can use a drag-and-drop interface to design and generate pivots that present different aspects of your data in the form of tables, charts, and other visualizations. You can learn more about the Pivot tool from the Splunk documentation1 or watch a video tutorial2. The other options are incorrect because they do not describe the features of the Pivot tool. The Pivot tool requires data models and datasets to define the data that you want to work with. Data models and datasets are designed by the knowledge managers in your organization. You can learn more about data models and datasets from the Splunk documentation3. The Pivot tool does not create lookups, which are tables that match field values to other field values. You can create lookups using SPL or the Lookup Editor. You can learn more about lookups from the Splunk documentation.