A C E it is

I believe A, C, E is correct.

I cannot find something like REST API login()

A:
- The username-password flow generates access tokens as Salesforce Session IDs that can’t be introspected.
- https://help.salesforce.com/s/articleViewid=sf.remoteaccess_oauth_username_password_flow.htm&type=5

C:
- Optional, a session ID to be used by endpoint URL client that is responding to the outbound message. It’s used by the receiving code to make calls back to Salesforce.
- https://developer.salesforce.com/docs/atlas.en-us.api.meta/api/sforce_api_om_outboundmessaging_wsdl.htm#i1473596

E:
- When a client app invokes the login() call, it passes in a username and password as credentials. Upon invocation, the API authenticates the credentials . It then returns the sessionId, the user ID associated with the logged-in username, and a URL that points to the Lightning Platform API to use in all subsequent API calls.
- https://developer.salesforce.com/docs/atlas.en-us.api.meta/api/sforce_api_calls_login.htm...