The correct answer is D. According to Coast Guard regulations, the captain's license examination is administered and supervised by the Coast Guard. The Coast Guard sets the standards for the content and format of the examination, as well as the procedures for administering it. Therefore, the correct answer is D, which indicates that the Coast Guard regulations govern the captain's license examination. The other answer choices (A, B, and C) do not accurately reflect the Coast Guard's role in regulating and overseeing the captain's license examination process.