What distinguishes x rays from gamma rays?

X-rays and gamma rays are both forms of electromagnetic radiation, but they originate from different processes, which is what distinguishes them. X-rays are produced primarily through interaction with electrons, specifically when high-energy electrons collide with a metal target or when electrons transition between energy levels in atoms. In contrast, gamma rays are emitted from the nucleus of radioactive atoms during radioactive decay or nuclear reactions. This key difference in the origin of their emission is what makes option B the correct choice.

The other options, while they describe characteristics of radiation, do not specifically differentiate between x-rays and gamma rays effectively. For instance, the frequency of emission pertains to the energy and wavelength of the radiation rather than the source type. The intensity of radiation relates to the amount of energy being emitted but does not clarify the differing origins. Similarly, the time of emission is not relevant to distinguishing between these two types of radiation as both can be emitted continuously or at discrete times depending on the physical processes involved. Thus, the origin of emission stands out as the definitive factor that clearly differentiates x-rays from gamma rays.