Using an image receptor holder with an external aiming device will most likely eliminate what error?

a. Overlapping
b. Unequal distribution of arches recorded
c. Cone cutting
d. Incorrect placement of the image receptor

c. The ring external aiming device is designed to match the round collimation of the PID. These devices make centering the image recept within the beam of radiation easy to achieve. (Rectangular cutouts within the round ring and rectangular aiming devices are also available that help to avoid cone-cut error when using a rectangular PID.)