You consider using the Dataverse web service for a new application. 
Please select all the types of Dataverse web services you can implement.

Answer options:

A.Azure SQL API
B.Web API
C.Fetch XML
D.Organization services
E.OData

Correct Answers: B and D 
The Dataverse provides the web services as extension tools for interacting with the data and metadata. The Dataverse web services include Web API and Organization service. If you prefer to write the .Net code, the Organization service approach is the best bet. The Web API provides almost the same functionality by using the REST API protocol. The Organization service implements two assemblies: SDK assembly and XRM Tooling assembly for the Windows clients.
Option A is incorrect because the Azure SQL API manages Azure SQL Database resources. It is not the part of the web services that the Dataverse provides for interaction with the data and metadata.
Option C is incorrect because the FetchXML is a query language that creates complex queries against the Dataverse data. Both Dataverse web services can use the FetchXML for their queries. The FetchXML is not a web service that the Dataverse provides for interaction with the data and metadata.
Option E is incorrect because the OData (OASIS Open Data Protocol) is an industry-standard for querying the data. The Dataverse Web API uses this protocol. The OData is not a web service that the Dataverse provides for interaction with the data and metadata.
For more information about Dataverse web services, please visit the below URLs: 

https://docs.microsoft.com/en-us/powerapps/developer/data-platform/work-with-data
https://docs.microsoft.com/en-us/learn/modules/common-data-service-web-api/1-introduction
https://docs.microsoft.com/en-us/learn/modules/common-data-service-web-api/5-fetch-xml