Explanation
Two statements about the Order Summary object that are accurate are:
It does not exist without the original Order object. An Order Summary is a record that represents the financial summary of an order that is received from anexternal system, such as B2C Commerce or B2B Commerce. An Order Summary has a master-detail relationship to the Order object, which means that it cannot exist without its parent Order record.
It is read-only for financial order data. An Order Summary contains financial order data, such as total amount, tax amount, discount amount, etc., that are populated from the external system when the order is created. These fields are read-only and cannot be edited in Order Management.
Verified References:
https://help.salesforce.com/s/articleView?id=sf.order_management_order_summary.htm&type=5

When building a flow for multiple locations, an administrator should consider the following challenges:
Multiple locations will introduce nested loops which can make the canvas substantially larger. For example, a flow that handles multiple fulfillment orders per order and multiple fulfillment order lines per fulfillment order will need to loop through both levels of records. This can make the flow more complex and harder to maintain.
Multiple locations can lead to limit exceptions. For example, a flow that queries or updates a large number of records across multiple locations may hit the SOQL query limit or the DML statement limit. To avoid this, an administrator should use bulkified actions and optimize the flow performance. References: Order Fulfillment Flows, [Flow Performance Best Practices]

The required amount of test code coverage when deploying an Apex class is 75%. This means that at least 75% of the Apex code must be covered by unit tests, and all of those tests must complete successfully. Verified Reference: https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_deploying_ant_deploy.htm

The object record that is created when customer returns a product after fulfillment is Return Order. A Return Order is a record that represents a return request for an order or part of an order. A Return Order has a lookup relationship to both Order Summary and Change Order objects, and it contains information such as the return reason, status, date, etc. Verified References:https://help.salesforce.com/s/articleView?id=sf.
order_management_return_order.htm&type=5

The object that is created and linked to the Order Summary when a customer cancels an order prior to fulfillment is Cancel Order. A Cancel Order is a record that represents a cancellation request for an order or part of an order. A Cancel Order has a lookup relationship to both Order Summary and Change Order objects, and it contains information such as the cancellation reason, status, date, etc. Verified Reference: https://help.salesforce.com/s/articleView?id=sf.order_management_cancel_order.htm&type=5