The correct answer is: D. Endoscopy.
Optic fibers are used in endoscopy to transmit images and light from a camera to a screen. This allows doctors to see inside the body without having to make a large incision.
CAT scans, X-ray photos, and ultrasound scans are all medical imaging techniques that use different technologies to create images of the inside of the body. CAT scans use X-rays to create cross-sectional images of the body, while X-ray photos use X-rays to create two-dimensional images of the body. Ultrasound scans use sound waves to create images of the body.
Optic fibers are not used in CAT scans, X-ray photos, or ultrasound scans.