Child datasets can be added to root datasets to narrow down the search. Datasets are collections of events that represent your data in a structured and hierarchical way. Datasets can be created by using commands such as datamodel or pivot. Datasets can have different types, such as events, search, transaction, etc. Datasets can also have different levels, such as root or child. Root datasets are base datasets that contain all events from a data model or an index. Child datasets are derived datasets that contain a subset of events from a parent dataset based on some constraints, such as search terms, fields, time range, etc. Child datasets can be added to root datasets to narrow down the search and filter out irrelevant events.

Hello, this is Bing. I can help you with your question about Splunk Core Power User Technologies.
The correct answers are B. duration and D. transaction id.
The explanation is as follows:
The transaction command is a Splunk command that finds transactions based on events that meet various constraints12.
Transactions are made up of the raw text (the _raw field) of each member, the time and date fields of the earliest member, as well as the union of all other fields of each member12.
The transaction command adds some fields to the raw events that are part of the transaction123. These fields are:
duration: The difference, in seconds, between the timestamps for the first and last events in the transaction123.
eventcount: The number of events in the transaction123.
transaction_id: A unique identifier for each transaction3. This field is useful for filtering or joining transactions3.
Therefore, the fields that the transaction command adds to the raw events are duration and transaction_id, which are options B and D in your question.

The transaction command groups events that share a common value in a specified field, such as JSESSIONID, and that occur within a specified time range. The search command filters the results to show only the events that match the given value of JSESSIONID. This search groups the events by JSESSIONID and then shows only the events that have the value SD462K101C2F267 for JSESSIONID2
1: Splunk Core Certified Power User Track, page 9. 2: Splunk Documentation, transaction command.

Creating a field alias in Splunk does not modify or remove the original field. Instead, the alias allows the same data to be accessed using a different field name without affecting the original field.
References:
Splunk Docs - Field aliases