Explanation: Harmonic radiation consists of unintended signals transmitted at integer multiples of your fundamental operating frequency. These emissions, even if weaker than the primary signal, can cause significant interference. Option A is correct because harmonics can propagate differently than the fundamental. For instance, a harmonic frequency might "skip" via the ionosphere to distant locations where the fundamental signal, due to its frequency or power, cannot be heard. This can cause interference to other services operating on the harmonic frequency, far from the transmitting station. Option B is also correct. Harmonics can interfere locally with other electronic equipment, such as radios, navigation systems, or computers on the same ship, in a home, or other confined environments. This is due to the strong radiated fields or conducted signals within close proximity. Since harmonic radiation can cause both long-distance skip interference and local equipment interference, option C, which includes both scenarios, is the most comprehensive and correct answer.