C. coil suspended by bearings.
<span>but im not 100% sure</span>
Explanation:
As we know that relation between energy and wavelength is as follows.
E = 
This means that energy is inversely proportional to wavelength. So, more is the energy of an electromagnetic radiation less will be its wavelength.
Also, f = 
Hence, less will be the wavelength more will frequency of a radiation.
Gamma rays are the rays that have highest energy, small wavelength and highest frequency.
Thus, we can conclude that gamma rays are the electromagnetic radiation which has the highest frequency.