**Core Concept**
Non-ionic contrast agents are a type of iodinated contrast medium used in radiographic imaging to enhance the visibility of internal structures. Unlike ionic contrast agents, non-ionic agents have a lower osmolality, which reduces the risk of adverse reactions.

**Why the Correct Answer is Right**
Non-ionic contrast agents work by being taken up by the blood vessels, which enhances the contrast between the blood vessels and the surrounding tissues. This allows for better visualization of internal structures during imaging procedures. Examples of non-ionic contrast agents include iohexol and iopamidol, which are commonly used in computed tomography (CT) scans and other radiographic imaging procedures.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not specified, but it is likely that it would be an ionic contrast agent, such as diatrizoate, which has a higher osmolality and is associated with a higher risk of adverse reactions.
**Option B:** This option is also not specified, but it may refer to a different type of contrast agent, such as a gadolinium-based contrast agent, which is used in magnetic resonance imaging (MRI) procedures.
**Option C:** This option is not specified, but it may refer to a barium-based contrast agent, which is used in gastrointestinal imaging procedures.

**Clinical Pearl / High-Yield Fact**
Non-ionic contrast agents are generally considered safer than ionic contrast agents and are preferred for patients with a history of allergies or kidney disease.

**Correct Answer: C. Iohexol**