Explanation: To upgrade a Second Class Radiotelegraph Operator license to First Class, an individual must pass additional examination elements, specifically Element 7. Commercial Operator License Examination Managers (COLEMs) administer these examinations. Upon successfully passing Element 7, the applicant receives a Proof-of-Passing Certificate (PPC). To complete the upgrade, these PPCs, along with the required fee and FCC Form 756, must be submitted to the Federal Communications Commission (FCC) for processing and license issuance. This process is standard for obtaining and upgrading commercial radio operator licenses in the U.S. Option B is incorrect because the Six Months Service Endorsement certifies operating experience, but it does not upgrade the class of a radiotelegraph license. Option C is incorrect; while experience is valuable, license upgrades are achieved by passing required examinations, not solely by presenting experience certifications to an examination manager. Option D is incorrect as ITU provisions are international regulations; they do not specify the domestic administrative process for upgrading a US commercial radio operator license, which falls under FCC rules.