Which type of radio is best used for international broadcasting?

The correct choice for international broadcasting is short-wave radio. Short-wave radio frequencies, typically between 3 and 30 MHz, are well-suited for long-distance communication because they reflect off the ionosphere, allowing broadcasts to be received over vast distances, including across countries and continents. This capability makes short-wave radio a preferred choice for international broadcasters aiming to reach audiences around the world.

Medium-wave radio, while capable of covering larger geographic areas, primarily operates within a range that limits its effectiveness for true global reach. Long-wave radio tends to be used for regional broadcasting several hundred kilometers from the transmitter due to its long wavelength, which does not allow for the same range as short-wave. Ultra high frequency radio operates at frequencies above 30 MHz, which, although effective for local and regional coverage, does not support long-distance broadcasting as well as short-wave does.

Thus, for international broadcasting, short-wave radio stands out as the most effective option.