What Is a Practical Applications of the Photoelectric Effect in Which

What is a practical applications of the photoelectric effect in which photoelectricity converts X-ray photons into electrical currents whose strength can be converted into a picture of the internal structure of an object?

A) camera light meters
B) fiber optics in some telephone audio systems
C) CAT scans
D) a battery operated flashlight
E) the standard X-ray machine in a small medical office