In frequency modulation (A) Frequency of carrier wave varies according to the frequency of signal. (B) Frequency of carrier wave varies according to the amplitude of the signal. (C) Frequency of signal varies according to the amplitude of carrier wave. (D) Frequency of signal varies according to the frequency of carrier wave Correct Ans: (B) Explanation: Frequency modulation (FM) is a key technique used in radio broadcasting and communication systems. In this process, the frequency of the carrier wave changes based on the amplitude of the signal. This method ensures clear audio quality and resistance to noise, making FM superior to amplitude modulation (AM) in many cases. Unlike AM, where the signal's strength varies, FM alters the wave’s frequency while keeping its amplitude constant. This technique helps reduce interference from electrical devices and atmospheric disturbances, providing better sound quality and less distortion. FM radio stations operate within a specific frequency range. For example, most FM broadcasts fall between 88 MHz and 108 MHz. Each station is assigned a narrow bandwidth, allowing for high-fidelity audio transmission. Due to its noise resistance, FM is widely used in public broadcasting, aviation, and emergency communication systems. However, FM also has limitations. It requires more bandwidth compared to AM, which limits the number of stations in a given range. Additionally, FM signals are more affected by obstacles like buildings and terrain, making them less effective for long-distance communication. Despite these challenges, FM remains a preferred choice for high-quality audio broadcasting. It provides reliable, interference-free communication, making it essential for radio stations, telecommunications, and various wireless technologies worldwide.