The merge code syntax for accessing a node from an Integration Procedure output is {{ProcedureName:
NodeName}}. In this case, the ProcedureName is HTTPGetCaseDetails and the NodeName is CaseData. The
% sign is used for single-value merge codes, not node merge codes. The $ sign is used for variables, not merge codes.

In Expression Sets, for any intermediate step (like Calculation) to be referenced in subsequent steps, such as Aggregation, the value must be made available via Output.
* B. It must be included in the output - Correct. Each step has an " Include in Output " checkbox. If not checked, its result is not accessible to following steps like Aggregation or Sub Expression.
Incorrect Options:
* A. Constants are global but do not affect step dependency.
* C. It does not have to be a Calculation Step; any previous step's output can be used if exposed.
Salesforce OmniStudio # Expression Sets - Step Configuration

A Set Values Action in a Value field and a Remote Action in an Additional Output value field can execute a function like CONCAT or DATEDIFF by using the syntax {{function(parameters)}}. For example,
{{CONCAT('Hello', 'World')}} or {{DATEDIFF('2021-01-01', '2021-01-31')}}.

The Repeatable Mode property on the data table elements allows the developer to display multiple records in a single data table. The Repeat Records feature on the FlexCard Setup tab is used to display multiple FlexCards for each record in a data source. The Record Looping feature on the data table elements is used to iterate over a list of records and perform actions on each record. The Overwrite Target for all Null input checkbox on the Account id field is used to overwrite the existing value in the target object with null if the input value is null.

The correct answer is D. Data Mapper Turbo Extract, based on best practices in the official OmniStudio documentation.
From the OmniStudio Developer Guide # DataRaptors # Turbo Extract:
* DataRaptor Turbo Extract is a lightweight, high-performance extract designed specifically for retrieving data from a single Salesforce object, where no data transformation or complex joins are required.
* It is recommended over DataRaptor Extract for performance reasons when only one object and minimal transformation is needed.
Why not the others?
* A. DataRaptor Load is used for writing data to Salesforce, not retrieving.
* B. DataRaptor Transform is used when you need to transform data, not simply extract it.
* C. DataRaptor Extract can be used, but Turbo Extract is preferred for the use case of single object, no transformation - per best practices.
Salesforce OmniStudio Developer Guide # DataRaptor Turbo Extract Best Practices OmniStudio Certification Study Guide # " When to use Turbo Extract "