Which of the following NR slot configurations are defined in 3GPP specifications?

A. Mixed slot is a slot configuration in which at least one downlink/uplink symbol is present, while other symbols can be flexibly configured for downlink or uplink transmission. This allows for a more efficient use of resources and better support for different types of services. B. Flexible-slot is a slot configuration in which all symbols are flexibly configured for downlink or uplink transmission. This allows for a more efficient use of resources and better support for different types of services. C. Downlink-only slot is a slot configuration in which all symbols are dedicated for downlink transmission, This configuration is mainly used for downlink-centric services such as video streaming or software downloads. D. Uplink-only slot is a slot configuration in which all symbols are dedicated for uplink transmission, this configuration is mainly used for uplink-centric services such as voice calls or video conferencing.