Explanation: Part 13 of the FCC Rules, which governs Commercial Radio Operators, historically outlined specific requirements for various radiotelegraph licenses. For a First Class Radiotelegraph Operator's License, the FCC required an applicant to be at least 21 years of age at the time of application. This specific age requirement was unique to the First Class license, reflecting the advanced responsibilities and experience expected of its holders. Other options are incorrect because: A) There was no specific 18-year age requirement for a Second Class Radiotelegraph Operator's License; applicants generally needed to be of sufficient age to hold a commercial license, typically 18 for most, but not a specific rule like the First Class. C) A person would have had to meet the 21-year age requirement to *obtain* a First Class license initially, making it impossible for someone under 21 to "now hold" one that was validly issued under those rules. Renewal rules generally focus on continued competence, not re-meeting initial age.