**Core Concept**
Radiation exposure in medical imaging occurs due to the use of ionizing radiation, which can cause damage to living tissues. The maximum radiation exposure is a critical consideration in medical imaging, as it can increase the risk of radiation-induced injuries and malignancies.

**Why the Correct Answer is Right**
The maximum radiation exposure is typically associated with fluoroscopy, a type of medical imaging that uses X-rays to produce real-time images of the body. During fluoroscopy, the X-ray beam is focused on a specific area of the body, and the image is displayed on a monitor. The radiation exposure is highest when the X-ray beam is directed at a small area of the body for an extended period, such as during procedures like barium swallow studies or joint injections. This is because the radiation dose is concentrated in a small area, leading to higher exposure.

**Why Each Wrong Option is Incorrect**
**Option A:** Computed Tomography (CT) scans involve the use of X-rays, but the radiation exposure is typically lower than that of fluoroscopy because the X-ray beam is focused on a larger area and the scan is usually shorter.
**Option B:** Mammography involves the use of low-energy X-rays, which result in lower radiation exposure compared to fluoroscopy.
**Option C:** Plain radiography, such as chest X-rays, typically involves lower radiation exposure compared to fluoroscopy because the X-ray beam is focused on a larger area and the exposure time is shorter.

**Clinical Pearl / High-Yield Fact**
To minimize radiation exposure, medical imaging procedures should be performed using the lowest possible dose of radiation, and alternative imaging modalities such as ultrasound or magnetic resonance imaging (MRI) should be considered when possible.

**Correct Answer: C. Plain radiography.