What are the two primary units used to measure exposure to radiation?

The two primary units used to measure exposure to radiation are Coulombs per kilogram (C/kg) and Roentgen (R). These units specifically relate to the measurement of ionizing radiation exposure in air. The Roentgen is a traditional unit that quantifies the amount of ionization produced in air by x-rays or gamma rays, while Coulombs per kilogram is a unit that expresses the amount of electrical charge (in coulombs) produced by ionizing radiation in a mass of air (in kilograms).

Both of these units are crucial for assessing the amount of radiation exposure received by individuals and are particularly important in the field of radiology and radiation safety. They help professionals determine the risks associated with exposure to radiation and implement appropriate safety measures.

Other choices either focus on different aspects of radiation measurement or use units that are not primarily concerned with measuring exposure directly. For instance, Sieverts and Grays are more associated with dose and absorbed dose rather than direct exposure, while Becquerel measures radioactivity, and Hertz is a unit of frequency not relevant to radiation exposure.