Which of the following frequencies is within the General class portion of the 15-meter band?

To answer this question correctly, you must know the frequency limits of the amateur radio bands. The 15-meter band spans from 21.000 MHz to 21.450 MHz, which can also be expressed as 21000 kHz to 21450 kHz. Among the options provided, only 21300 kHz falls squarely within the 15-meter band. Furthermore, it is within the General class phone (voice) privileges, which run from 21275 kHz to 21450 kHz. Looking at the distractors, 14250 kHz is in the 20-meter band, 18155 kHz is in the 17-meter band, and 24900 kHz is in the 12-meter band. Memorizing the general MHz starting points (e.g., 15 meters is 21 MHz) easily eliminates the wrong choices.