**Core Concept**
Nuclear medicine is an imaging modality that utilizes small amounts of radioactive materials, also known as radiopharmaceuticals, to diagnose and treat various medical conditions. It combines the principles of nuclear physics, chemistry, and medicine to visualize and quantify the function of various organs and tissues within the body.

**Why the Correct Answer is Right**
The correct answer is related to the use of radiopharmaceuticals in nuclear medicine. These substances are designed to target specific tissues or organs, allowing for the visualization of their function and structure. The process involves the administration of a small amount of radioactive material, which is then detected by a gamma camera or other imaging device. This enables the creation of detailed images of the targeted area, providing valuable information for diagnosis and treatment.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe a characteristic of nuclear medicine.
**Option B:** This option is incorrect because it is more closely related to magnetic resonance imaging (MRI) rather than nuclear medicine.
**Option C:** This option is incorrect because it is not a defining feature of nuclear medicine.

**Clinical Pearl / High-Yield Fact**
One of the key benefits of nuclear medicine is its ability to provide functional information about the body's organs and tissues. This is in contrast to other imaging modalities, such as X-ray or CT scans, which primarily provide anatomical information.

**Correct Answer: C. Imaging with radiopharmaceuticals.**

✓ Correct Answer: D. Field of medicine which depends on accretion, transit & disappearance of radioactive tracer in specific regions of body & useful in management of cancer.