Which of the following displays is primarily used for volumetric imaging in ultrasonic testing?

The C-scan display is primarily used for volumetric imaging in ultrasonic testing because it provides a two-dimensional representation of the ultrasonic data over a specified area or volume of the test object. This display format allows for comprehensive visualization of internal features and anomalies by plotting the amplitude or intensity of the received ultrasonic signals across a scanned area, effectively creating a "slice" view of the material being inspected.

In C-scan displays, the data is often represented in a color map, making it easier to identify and interpret various features, such as flaws or variations in material properties, within the scanned volume. This is crucial for assessing the integrity of components, especially in applications where three-dimensional consideration is necessary for evaluating complex geometries or composite materials.

In contrast, A-scan displays provide a simple one-dimensional view of the time-domain signal received from a single transducer, which shows amplitude versus time rather than spatial location. B-scan displays offer a two-dimensional slice through a material, but do not provide full volumetric assessment like the C-scan. There is no standard D-scan display used in ultrasonic testing, which also differentiates the C-scan as the correct choice for volumetric imaging.