Explanation: Commercial radiotelegraph licenses require demonstrated proficiency in receiving International Morse Code. FCC regulations for these licenses mandate an examination element where the applicant must accurately receive Morse code messages by ear. Option C accurately reflects this requirement, specifying a period of one minute without error, which is a common standard for demonstrating basic receiving competence at a given speed. Option A is incorrect because the examination for Morse code proficiency has a very specific format centered on accurate reception, not just any format to ascertain comprehension. Option B lists formats common to written theory exams, not the practical receiving test for Morse code, although "one minute solid copy" is relevant. Option D is incorrect because the primary measure for Morse code reception is the accuracy of the copy itself, often requiring error-free reception, rather than simply achieving a passing score on subsequent comprehension questions.