Answer:
A. Gamma rays have more energy than radio waves and could harm people.
Step-by-step explanation:
Those waves contains high energy, which have high frequency and shorter wavelength. Gamma rays are electromagnetic waves which have higher energy due to shorter wavelength and highest frequency. Due to the presence of high energy, gamma radiations destroy living cells of animals and plants and causes many dangerous diseases like cancer. So that's why gamma radiation cannot be used in the radar system.