Reference:
A calculated field is a field that you create based on the value of another field or fields1. You can use calculated fields to enrich your data with additional information or to transform your data into a more useful format1. Calculated fields can be based on extracted fields, which are fields that are extracted from your raw data using various methods such as regular expressions, delimiters, or key-value pairs1. Therefore, option B is correct, while options A, C and D are incorrect because tags, output fields for a lookup, and fields generated from a search string are not types of extracted fields.

A comparison operator is a symbol that compares two values and returns a Boolean result (true or false)2. Splunk supports various comparison operators such as <, >, =, !=, <=, >=, IN and LIKE2. However, ?= is not a valid comparison operator in Splunk and will cause a syntax error if used in a search string2. Therefore, option E is correct, while options A, B, C and D are incorrect because they are valid comparison operators in Splunk

https://docs.splunk.com/Documentation/Splunk/8.1.0/SearchReference/Chart
https://docs.splunk.com/Documentation/Splunk/8.1.0/SearchReference/Stats

The Field Extractor (FX) is a tool that helps you extract fields from your events using a graphical interface2. You can create a report using a custom field extracted by the FX and share it with other users in your organization2. However, if another user runs the shared report and no results are returned, there could be two possible reasons. One reason is that the extraction is private, which means that only you can see and use the extracted field2. To make the extraction available to other users, you need to make it global or app-level2. Therefore, option C is correct. Another reason is that the other user does not have access to the index where the events are stored2. To fix this issue, you need to grant the appropriate permissions to the other user for the index2. Therefore, option D is correct. Options A and B are incorrect because they are not related to the field extraction or the report.