Which of the following is a valid Group D call sign format for Technician class?

In the FCC's sequential call sign system, Group D call signs are the standard format issued to new Technician and General class licensees. This format consists of two letters, one number, and three letters (a 2x3 format), with the first letter typically being K or W. The call sign KF1XXX fits this 2x3 format perfectly. Distractors like KA1X (a 2x1 format) and W1XX (a 1x2 format) belong to Groups A and B, which are shorter, special formats reserved exclusively for Amateur Extra class licensees.