The type of workflow action that sends field values to an external resource (e.g. a ticketing system) is POST. A POST workflow action allows you to send a POST request to a URI location with field values or static values as arguments. For example, you can use a POST workflow action to create a ticket in an external system with information from an event.

The eval command is used to create new fields or modify existing fields based on an expression2. The eval command can perform various actions such as calculations, conversions, string manipulations and more2. One of the actions that the eval command can perform is to create or replace an existing field with a new value based on an expression2. For example, | eval status=if(status="200","OK","ERROR") will create or replace the status field with either OK or ERROR depending on the original value of status2. Therefore, option B is correct, while options A, C and D are incorrect because they are not actions that the eval command can perform.

An event type is a classification of events based on a search query, which allows for a static set of search criteria. In this case, option A (index=server_48 sourcetype=BETA_881 code=220) represents a simple search without transforming commands (e.g., stats, inputlookup). Event types cannot include transforming commands such as stats or lookup.
Reference:
Splunk Documentation - Event Types

Reference:
The eval command is used to create new fields or modify existing fields based on an expression2. The output of an eval expression is a calculated field, which is a field that you create based on the value of another field or fields2. You can use calculated fields to enrich your data with additional information or to transform your data into a more useful format2. Therefore, option B is correct, while options A, C and D are incorrect because they are not names of knowledge objects that represent the output of an eval expression.