The schema of an SAP Build Work Zone URL that is visible to end users is composed of the following elements:
The unique subdomain, which is a custom name chosen by the customer when creating the SAP Build Work Zone service instance.
The DWS datacenter, which is the region where the service instance is deployed, such as eu10, us10, or ap10.
The work zone type, which is either workzone for SAP Build Work Zone, standard edition, or workzoneadv for SAP Build Work Zone, advanced edition.
The suffix .ondemand.com, which is the domain name for SAP Cloud Platform applications.
Therefore, the correct schema is .ondemand.com.
The other options are incorrect because they do not follow the correct order or format of the URL elements. They also confuse the subaccount subdomain and the subaccount datacenter with the unique subdomain and the DWS datacenter. The subaccount subdomain and the subaccount datacenter are related to the SAP BTP subaccount that hosts the SAP Build Work Zone service instance, not the URL that is visible to end users.
References:
Introducing SAP Build Work Zone, Unit 2, Lesson 1, Slide 5
SAP Build Work Zone - Implementation and Administration, Unit 2, Lesson 2, Slide 6