**Core Concept:** Computed tomography (CT) scan is a medical imaging technique that utilizes X-rays and a computer to create detailed images of internal body structures. It has become a vital tool for diagnosing various medical conditions and guiding surgical interventions.

**Why the Correct Answer is Right:** CT scans were invented by a British radiologist named Sir Godfrey Hounsfield and an American physicist, Allan Cormack, who developed the mathematical model for CT scanning in 1967. Their groundbreaking work led to the first CT scanner being built in 1971, marking the birth of modern CT scanning.

**Why Each Wrong Option is Incorrect:**

A. Cormack-Hounsfield Unit (HU): Hounsfield Units (HU) are a numerical scale used to describe the attenuation of X-rays in CT scans. They are not a person, so Option A is incorrect.

B. Computed Angiography (CTA): CTA is a type of CT scan used to visualize blood vessels. It is a subset of CT scans, not the inventor.

C. Computed Tomography Angiography (CTA): Similar to CTA, CTA is another type of CT scan used for assessing blood vessels, not the inventor.

D. Magnetic Resonance Imaging (MRI): MRI is another imaging modality used to visualize internal body structures. It is a different technology from CT scans and was not involved in their invention.

**Clinical Pearl:** The development of CT scans revolutionized medical diagnostics and guided numerous treatments. Their inventors won the Nobel Prize in Physics in 1979, recognizing the significant impact of their work on modern medicine.

**Correct Answer:** D. Godfrey Hounsfield and Allan Cormack