Explanation: Practical RADAR systems operate at microwave frequencies primarily because these shorter wavelengths allow for the use of highly directional antennas within a practical physical size. Concentrating the transmitted power into a very narrow beam ensures more energy illuminates the target. This focused energy, when reflected by the target, returns a stronger echo signal to the equally directional receiving antenna, thereby producing stronger target echoes and improving detection range and accuracy. Options B, C, and D are incorrect. Ground clutter can often be *more* significant at microwave frequencies due to reflections from small ground objects. Interference to other systems is never eliminated, but rather managed through frequency allocation. Lastly, highly *directional* antennas are crucial for radar to pinpoint targets and concentrate power, not non-directional ones.