What does 1 Gray equal in terms of absorbed dose?

The correct choice highlights that 1 Gray is equivalent to 1 Joule per kilogram. The Gray is the SI (International System of Units) unit of absorbed dose, which measures the amount of energy deposited by radiation in a given mass of matter. Specifically, it quantifies the absorption of one joule of radiation energy by one kilogram of tissue. This standardization is important in fields like radiology and radiation protection, where accurate measurement of radiation's biological effects on tissue is critical.

Understanding the relationship between energy absorption and mass is essential for calculating doses in medical and industrial applications where radiation is used. The other options, while they relate to radiation measurement, do not accurately express the definition of the Gray. For instance, rads and rems are older units that are used in the context of biological effects and do not describe the physical measurement of absorbed dose in the same direct way as the Joule per kilogram.