I think composite is more complex than ”simple” REST.

Inserts should be happening every 30 mins as per the question. So after every 30 minutes, a composite request should be created and hit to target system, to insert all new leads created in that 30 minutes. Simple Rest API can insert only one record at a time which does not have to wait for 30 mins. SO A& B are the answer

Composite is not needed in this case. Standard API should suffice.

According to this blog (https://sfdclesson.com/2023/07/13/seamless-integration-harnessing-the-power-of-salesforce-composite-api/#:~:text=Bulk%20data%20loading%3A%20You%20can,API%20calls%20and%20improving%20performance.) which states "You can use the composite resource to insert, update, or delete multiple records in one call, reducing the number of API calls and improving performance" the answers should be A and B

Correct Answer is A&D. Composite Rest API is not necessarily intended to aggregate multiple records of the same object into a single call but perform chain API calls relating different Object Records in one request. E.g. Insert Account + Opportunity associated to the returned new Account Record Id.

I think A & D The requirement in the scenario is to ensure that new leads are available in the new Salesforce instance within 30 minutes. Using the Composite REST API to aggregate multiple leads in a single call would require waiting until a certain number of leads are collected before sending them to the target system. This delay may not be acceptable for the sales department, which requires real-time access to new leads. Additionally, setting up the Composite REST API to aggregate leads would require custom development, which goes against the requirement of choosing approaches that require the least amount of development effort.

Why Saleforce put such confusing questions ? Whereas both answers seems to be correct like Composit API and REST API : if both APIs are used as Standard not Customization. So why confusing questions asked by Salesforce in Exam without elaborating Use Case... In question : Which two approaches will require the least amount of development effort? Ans is A & B: A. Configure named credentials in the source org. Its is clear to all. So I guess no need of explanation. B. Use the Composite REST API to aggregate multiple leads in a single call. Because its standard salesforce API no need to do any customization and it includes multiple and both Parent (Lead) and their associated Childs without code as its Salesforce Standard feature.

As per requirment old org will remain for some time and it will be merged with new one. Named credentioal is clear but what why composit RESt API is needed? it is very clear new records can be moved to new(target) org with Rest API. This option should be correct. any thought on this?