**Core Concept**
Iodine-containing contrast media are commonly used in radiographic imaging to enhance the visibility of structures within the body. However, there are alternative contrast agents that do not contain iodine, which are used in specific situations due to their unique properties.

**Why the Correct Answer is Right**
The correct answer is a non-iodine containing contrast agent that is used in magnetic resonance imaging (MRI). This type of contrast agent is based on the principle of magnetic resonance and is designed to alter the magnetic properties of hydrogen nuclei in the body, thereby enhancing the contrast in MRI images. Gadolinium-based contrast agents are the most common type of non-iodine containing contrast used in MRI.

**Why Each Wrong Option is Incorrect**
* **Option A:** Iodinated contrast media are the most common type of contrast agent used in radiographic imaging and contain iodine.
* **Option B:** Barium sulfate is a type of contrast agent used in gastrointestinal imaging, but it contains barium, not iodine.
* **Option D:** No information is provided for this option, making it an invalid distractor.

**Clinical Pearl / High-Yield Fact**
It's essential to note that non-iodine containing contrast agents like gadolinium-based agents are contraindicated in patients with severe kidney disease, as they can cause nephrogenic systemic fibrosis.

**Correct Answer:** C. Gadolinium-based contrast agents.