When creating a Search workflow action, which field is required?

[Reference: https://docs.splunk.com/Documentation/Splunk/8.0.3/Knowledge/Setupasearchworkflowaction, A workflow action is a link that appears when you click an event field value in your search results2. A workflow action can open a web page or run another search based on the field value2. There are two types of workflow actions: GET and POST2. A GET workflow action appends the field value to the end of a URI and opens it in a web browser2. A POST workflow action sends the field value as part of an HTTP request to a web server2. When creating a Search workflow action, which is a type of GET workflow action that runs another search based on the field value, the only required field is the search string2. The search string defines the search that will be run when the workflow action is clicked2. Therefore, option A is correct, while options B, C and D are incorrect because they are not required fields for creating a Search workflow action., , ]