Explanation
By default, acceleration is determined automatically based on the data source in the Splunk Common Information Model (CIM) add-on. The Splunk CIM Add-on is an app that provides common data models for various domains, such as network traffic, web activity, authentication, etc. The CIM Add-on allows you to normalize and enrich your data using predefined fields and tags. The CIM Add-on also allows you to accelerate your data models for faster searches and reports. Acceleration is a feature that pre-computes summary data for your data models and stores them in tsidx files. Acceleration can improve the performance and efficiency of your searches and reports that use data models.
By default, acceleration is determined automatically based on the data source in the CIM Add-on. This means that Splunk will decide whether to enable or disable acceleration for each data model based on some factors, such as data volume, data type, data model complexity, etc. However, you can also manually enable or disable acceleration for each data model by using the Settings menu or by editing the datamodels.conf file.

The correct answer is D. field2 values are replaced with the value of the field1.
A field alias is a way to associate an additional (new) name with an existing field name. A field alias can be used to normalize fields from different sources that have different names but represent the same data. Field aliases can also be used to rename fields for clarity or convenience1.
When you create a field alias in Splunk Web, you can select the Overwrite Field Values option to change the behavior of the field alias. This option affects how the Splunk software handles situations where the original field has no value or does not exist, as well as situations where the alias field already exists as a field in your events, alongside the original field2.
If you select the Overwrite Field Values option, the following rules apply:
If the original field does not exist or has no value in an event, the alias field is removed from that event.
If the original field and the alias field both exist in an event, the value of the alias field is replaced with the value of the original field.
If you do not select the Overwrite Field Values option, the following rules apply:
If the original field does not exist or has no value in an event, the alias field is unchanged in that event.
If the original field and the alias field both exist in an event, both fields are retained with their respective values.
Therefore, if you create a field alias where field1-field2 and select the Overwrite Field Values option, and an event only contains values for field1, then the value of field2 will be replaced with the value of field1.
Reference:
About calculated fields
About field aliases
Create field aliases in Splunk Web

When defining a search macro, the required elements are the name and the definition of the macro. The name is a unique identifier for the macro that can be used to invoke it in other searches. The definition is the search string that the macro expands to when referenced. The arguments, validation expression, and validation error message are optional elements that can be used to customize the macro behavior and input validation2
1: Splunk Core Certified Power User Track, page 9. 2: Splunk Documentation, Define search macros in Settings.

Explanation/Reference: https://docs.splunk.com/Documentation/CIM/4.15.0/User/Overview