Field aliases can be applied at the level of event types to rename or alias fields without modifying the raw data. They do not apply to tags, indexes, or sourcetypes directly.
Reference:
Splunk Power User Study Guide, Knowledge Objects
Splunk Docs: Field Aliases
"Field aliases can be assigned to event types to map one field name to another."

When using a field value variable with a Workflow Action, the exclamation mark (!) will escape the data. A Workflow Action is a custom action that performs a task when you click on a field value in your search results. A Workflow Action can be configured with various options, such as label name, base URL, URI parameters, post arguments, app context, etc. A field value variable is a placeholder for the field value that will be used to replace the variable in the URL or post argument of the Workflow Action. A field value variable is written as fieldname, where field_name is the name of the field whose value will be used.
However, if the field value contains special characters that need to be escaped, such as spaces, commas, etc., you can use the exclamation mark (!) before and after the field value variable to escape the data. For example, if you have a field value variable host, you can write it as !$host! to escape any special characters in the host field value.
Therefore, option B is the correct answer.

To retrieve data from an external resource based on a field like Zip_Code, a GET workflow action is appropriate. GET requests retrieve information by passing the Zip_Code as a parameter to an external URL, commonly used in weather APIs.
Reference:
Splunk Power User Study Guide, Workflow Actions
Splunk Docs: Workflow Actions
"GET workflow actions are used to retrieve external data using URL parameters from event fields."

A workflow action is a link that appears when you click an event field value in your search results1. A workflow action can open a web page or run another search based on the field value1. There are two types of workflow actions: GET and POST1. A GET workflow action appends the field value to the end of a URI and opens it in a web browser1. A POST workflow action sends the field value as part of an HTTP request to a web server1. You can configure a workflow action to open a web page in either the same window or a new window1. Therefore, option D is correct, while options A, B and C are incorrect.