What is the unit of measure for radiation exposure in air?

The correct choice for the unit of measure for radiation exposure in air is Roentgen (R). This unit specifically quantifies the amount of ionization produced in the air by X-rays or gamma rays. The Roentgen measurement is particularly relevant for assessing exposure because it reflects the potential biological effects of the radiation when it interacts with air, which is crucial for ensuring safety and protection measures.

Other units mentioned serve different purposes. The Gray (Gy) is used to measure absorbed dose, indicating the amount of energy deposited in a tissue or material, but does not specifically measure exposure in air. The Becquerel (Bq) quantifies radioactivity, representing the number of decays per second of a radioactive substance, rather than measuring exposure directly. The Sievert (Sv) is a unit that takes into account the biological effect of radiation, providing an assessment of the dose in terms of its potential health impacts, rather than focusing on air exposure alone. Thus, the Roentgen is uniquely suited for this specific measure of radiation exposure in the atmosphere.