Which two units are used to measure the absorption of radiation?

The correct choice highlights the units used for measuring the absorption of radiation. The gray, which is abbreviated as Gy, is the SI unit used for the measurement of absorbed dose in radiation physics, reflecting the amount of energy deposited by ionizing radiation in a unit mass of tissue. A dose of one gray indicates that one joule of radiation energy has been absorbed per kilogram of tissue.

The rad, which stands for radiation absorbed dose, is an older unit that was commonly used before the introduction of the gray. One rad is equivalent to 0.01 gray, so it also serves as a measure of absorbed radiation. Although the gray is the standard unit used in modern applications, the rad is still relevant for historical context and certain medical practices.

The relationship between these two units clearly defines their specific roles in radiation measurement, with both the gray and the rad focused specifically on the amount of energy absorbed by the body.