Colleen replicates an x-ray machine by covering an open shoebox with the screen and positioning a square cardboard piece in the center she uses sand to stimulate x-ray radiation sprinkling it all over the screen upon removing the screen she observes an outline of the square cardboard what does the cardboard symbolize in a simulation.
A. the areas that remain black on the X rat
B. the bones that look white in an X ray
C. the vein that look white in an X ray
D. the person being scanned with X rays