Each of the following statements regarding preparations for bitewing exams is correct EXCEPT one. ...

Each of the following statements regarding preparations for bitewing exams is correct EXCEPT one. Which one is the EXCEPTION?
 
  a. The dental x-ray machine should be turned on and the exposure setting selected prior to placing the image receptor intraorally.
  b. The radiographic procedure should be explained to the patient prior to beginning the exposures.
  c. The patient's head should be positioned with the mean tangent parallel to the floor.
  d. The patient should be asked to remove eyeglasses and all intraoral appliances prior to placement of the image receptor.