During the validation step of the Field Extractor workflow, you can remove values that aren't a match for the field you want to define2. The validation step allows you to review and edit the values that have been extracted by the FX and make sure they are correct and consistent2. You can remove values thataren't a match by clicking on them and selecting Remove Value from the menu2. This will excludethem from your field extraction and update the regular expression accordingly2. Therefore, option A is correct, while options B and C are incorrect because they are not actions that you can perform during the validation step of the Field Extractor workflow.

Field aliases are used to normalize different field names that contain the same type of data (like IP addresses) across multiple sourcetypes or sources, making the data CIM compliant without re-extracting the fields.
Reference:
Splunk Power User Study Guide, CIM Compliance
Splunk Docs: Field Aliases for CIM
"Field aliases normalize field names across data sources for CIM compliance."

A space is an implied AND in a search string, which means that it acts as a logical operator that returns events that match both terms on either side of the space2. For example, status=200 method=GET will return events that have both status=200 and method=GET2. Therefore, option B is correct, while options A, C and D are incorrect because they are not implied by a space in a search string.

When using multiple expressions in a single eval command in Splunk, the delimiter used is a comma (,). This allows for the execution of multiple operations within a single eval statement, separating each operation clearly.
References:
* Splunk Docs: Eval command
* Splunk Answers: Multiple expressions in eval