**Core Concept**
The question is testing the student's knowledge of the fundamental units used in radiation measurement. Radiation absorption is a critical concept in medical physics, particularly in radiation oncology and nuclear medicine.

**Why the Correct Answer is Right**
The correct unit for radiation absorption is the Gray (Gy). The Gray is defined as the absorption of one joule of radiation energy per kilogram of matter. This unit is widely used to express the absorbed dose of radiation in the International System of Units (SI). The Gray is a measure of the energy deposited in a mass of tissue, and it is essential for calculating radiation doses in various medical applications.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not represent a valid unit for radiation absorption.
* **Option B:** This option is incorrect because it represents a unit of radiation exposure, not absorption.
* **Option C:** This option is incorrect because it is not a unit of radiation absorption.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that the Gray is a fundamental unit in radiation oncology, and it is used to calculate radiation doses for patients undergoing radiation therapy. A dose of 2 Gy is equivalent to 200 rads.

**Correct Answer: C. Gray (Gy)**