A is correct because creating a connected app that supports the JWT Bearer Token OAuth Flow allows the middleware to authenticate to Salesforce without storing usernames and passwords.The JWT Bearer Token OAuth Flow uses a certificate and a private key to sign a JSON Web Token (JWT) that contains information about the user identity andrequested access. The middleware sends the JWTto Salesforce, which verifies it using the certificate and grants an access token2.

B is incorrect because creatinga connected app that supports the Refresh Token OAuth Flow requires storing usernames and passwords in the middleware. The Refresh Token OAuth Flow uses a username-password authentication flow to obtain an access token and a refresh token. The middleware can use the refresh token to obtain new access tokens without user interaction, but it still needs to store the username and password for the initial authentication3.

C is incorrect because creating a connected app that supports the Web Server OAuth Flow requires user interaction to authenticate to Salesforce. The Web Server OAuth Flow redirects the user to a Salesforce login page, where they enter their credentials and grant access to the middleware. The middleware then receives an authorization code that it can exchange for an access token and a refresh token4.

D is incorrect because creating a connected app that supports the User-Agent OAuth Flow also requires user interaction to authenticate to Salesforce. The User-Agent OAuth Flow is similar to the Web Server OAuth Flow, except that it does not return a refresh token. The middleware can only use the access token until it expires5.