___________ is considered one of the most observed and critical components of non-verbal communication

a. Slumped shoulders
b. Patient seated with arm and legs crossed
c. Facial expression
d. Tight patient posture

c
RATIONALE: Facial expression is one of the most observed and critical components of non-verbal communication. The patient's face may reveal pain, fear, or anxiety. The dental assistant should be alert to non-verbal signals to be able to react appropriately to the patient.