Which of the following bands has the lowest maximum permissible exposure for RF safety?

The human body acts like a resonant antenna and absorbs radio frequency (RF) energy most efficiently in the VHF range, specifically between 30 MHz and 300 MHz. Because the body absorbs so much energy in this range, the Maximum Permissible Exposure (MPE) limits must be the most stringent, meaning they are the lowest. Looking at the options provided, 50 MHz (the 6-meter band) is the only frequency that falls within this highly absorptive 30-300 MHz window. Frequencies like 3.5 MHz (HF) or 440 MHz and 1296 MHz (UHF/Microwave) result in less efficient RF absorption by the human body, so their safe exposure limits are actually higher.