The Platform API and the Composite API are two ways that an administrator can use APIs in Workbench to query Order Summaries. The Platform API allows querying, creating, updating, deleting, and searching records in Salesforce. The Composite API allows combining multiple requests into a single call, which can improve performance and reduce complexity12

Three statements that are true about change sets are:
Sending a change set between two orgs requires a deployment connection. A deployment connection is a link between two orgs thatallows one org to send change sets to another org.
Change sets can only be sent between orgs that are affiliated with a production org. A production org is an org that is used for live operations and data, and it can have one or more sandbox orgs that areused for development and testing. Change sets can only be sent from a sandbox org to its associated production org, or from one sandbox org to another sandbox org that shares the same production org.
Change sets can contain only modifications made throughthe Setup menu. A change set is a collection of metadata components that can be deployed from one org to another. Metadata components are customizations that are made through the Setup menu, such as custom objects, fields, workflows, etc.
Verified References: https://help.salesforce.com/s/articleView?id=sf.changesets_about.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.changesets_components.htm&type=5

When a customer applies a discount when placing an order, an order adjustment group summary is created.
An order adjustment group summary is a record that represents a modification to the order amount,such as a discount, a surcharge, or a tax. An order adjustment group summary can have one or more order adjustments, which are the individual modifications that are applied to the order or the order items. An order can have one or more order adjustment group summaries, depending on how many types of modifications are applied to the order. References: Order Management Objects, [Order Adjustments]