You create an Azure Web App and want your Power Apps app to use a custom connector to consume the Azure Web App REST API. 
What tools should you consider for the creation of API definition?

Answer options:

A.OpenAPI
B.Web API
C.Blank custom connector
D.PCF Component
E.Postman Collection
F.Organization service

Correct Answers: A, C and E 
A custom connector is an API wrapper around the REST API. You can create such a wrapper for Azure Functions, Azure Web Apps, Azure API apps. 
When you create your application using one of these services, you need to describe the API`s operations before you can export your application`s APIs. There are three approaches to how to create the API definitions: Using a blank custom connector
Using an Open API definition
Using a Postman Collection
Then you need to secure your Web APIs and set the authentication type for your custom connector. In the end, when you test a new custom connector, you can use it in Poser Apps, Power Automate, and Azure Logic Apps. 
All other options are incorrect. 
For more information about creating API definitions, please visit the below URLs: 

https://docs.microsoft.com/en-us/connectors/custom-connectors/
https://docs.microsoft.com/en-us/connectors/custom-connectors/define-blank
https://docs.microsoft.com/en-us/connectors/custom-connectors/define-openapi-definition
https://docs.microsoft.com/en-us/connectors/custom-connectors/define-postman-collection