Explanation: Operating a fixed-tuned ship RADAR station using only its external controls does not require a specific FCC commercial radio operator license or endorsement. FCC regulations (Part 80, Subpart J) specify that a special authorization, such as a Ship RADAR Endorsement (or a higher-level license like a GROL, Radiotelegraph Operator Certificate, or GMDSS Radio Maintainer's Certificate), is required only for *making internal adjustments*, *servicing*, or *installing* the RADAR equipment. Simple operation of a properly maintained, fixed-tuned RADAR via external controls is considered a routine function that any competent crew member, under the direction of the ship's master, can perform without additional FCC licensing. Therefore, options A, B, and C are incorrect because they refer to licenses or endorsements required for technical work on the RADAR, not for its routine operation.