What is the area between the x-ray source and the image receptor that will be recorded in relative detail on the resultant radiograph called?

a. Negative shadow
b. Ghost image
c. Focal trough
d. Rotational center

c. The focal trough or focal layer is where the dental arches should be positioned to achieve the sharpest image. The focal trough is that area between the x-ray source and the image receptor that will be imaged distinctly on the panoramic radiograph.