https://docs.splunk.com/Documentation/Splunk/8.1.1/SearchReference/ConditionalFunctions

Explanation/Reference:

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.