Which of the following points 1 in. (2.5 cm) above the lower border of the mandible is the suggested landmark for directing the central ray of the x-ray beam when exposing the mandibular premolar...

Which of the following points 1 in. (2.5 cm) above the lower border of the mandible is the suggested landmark for directing the central ray of the x-ray beam when exposing the mandibular premolar radiograph using the bisecting technique?

a. The middle (symphysis) of the chin

b. The center of the root of the canine

c. Directly inferior to the pupil of the eye

d. Directly inferior to the outer canthus of the eye