Final answer:
Ultrasound, or ultrasonography, is the imaging technique that uses high-frequency sound waves to create images of the body's interior, particularly useful and safe during pregnancy and other medical assessments.
Step-by-step explanation:
The imaging technique that uses high-frequency sound waves to penetrate deep tissue layers is D) Ultrasound. Ultrasound, also known as ultrasonography, employs the transmission of high-frequency sound waves into the body which generate an echo signal that a computer converts into a real-time image of anatomy and physiology. This technique is particularly noninvasive and is commonly used in pregnancy monitoring, evaluation of heart function, identification of blood flow issues, and diagnosis of various conditions such as gallbladder disease. The sound frequencies used in ultrasonography are much higher than the human ear can hear and are therefore referred to as ultrasound. The technology is advantageous for its safety profile, making it the preferred choice during pregnancy over other imaging methods like X-rays, CT scans, and PET scans which involve electromagnetic radiation or ionizing radiation.
While ultrasonography is widely used, it is important to recognize that the image quality can depend on the operator's skill, and the technique cannot penetrate bone or gas.