Which of the following statements regarding image receptor holders is FALSE?

a. Short bite blocks should be used for the bisecting technique.
b. External aiming devices help locate correct angles and points of entry.
c. External aiming devices eliminate the need to position the patient's head precisely.
d. Bite blocks with an L-shaped back plate should be used with the bisecting technique.

d. Bite blocks with a 105-degree back plate should be used with the bisecting technique. The parallelling technique requires a bite block with an L-shaped (90?) back plate.