Explanation: Longer antennas, particularly those designed for directionality, generally exhibit higher gain. This increased gain is achieved by concentrating the transmitted radio frequency energy into a more focused radiation pattern. Think of it like focusing a flashlight beam: a more powerful lens (analogous to a longer, more directive antenna) creates a tighter, brighter spot. Therefore, a longer antenna typically results in a narrower horizontal beamwidth. The energy is directed more precisely in a specific azimuthal direction rather than being spread out broadly. This concentration of energy in a smaller angular sector is a fundamental characteristic of higher-gain antennas. Options A and C contradict this principle of antenna directivity and gain.