The correct answer is A. by providing the external application a token that authorizes access to the account.
In REST APIs, OAuth is used as an authorization framework. Instead of giving the external application the user's actual username and password, the user or authorization server provides the application with an access token. That token allows the application to access specific resources based on the permissions granted.
This is the main purpose of OAuth:
* Authorize access
* Use tokens instead of exposing credentials
* Allow controlled, limited access to resources
* B. as a framework to hide the security information in the REST URL OAuth does not work by hiding information in the URL. It is an authorization framework based on tokens.
* C. as a framework to hash the security information in the REST URL OAuth is not a URL-hashing mechanism. Hashing and OAuth are different concepts.
* D. by providing the user credentials to the external application This is the opposite of OAuth's purpose.
OAuth is designed so that the external application does not need the user's credentials.
Remember this difference:
* Basic Authentication # sends username/password
* OAuth # uses token-based authorization
OAuth = token-based delegated access