For implementing client credentials grant in a Spring Boot application, the client must send a request to the token endpoint with _____ grant type.

To implement the client credentials grant in a Spring Boot application, the client must send a request to the token endpoint with the client_credentials grant type. This grant type is used when the client, typically a service or application, needs to authenticate itself directly with the authorization server to obtain an access token. The other options are different OAuth2 grant types used for various scenarios.