Answer: b. "You appear to be having pain."
Explanation:
A grimacing is a kind of nonverbal communication. This involves the creation of facial expression by the person which is indicative of pain or disgust. The expressions are in the form of comic exaggeration. For example, this can be interpreted through signs like when a person makes wrinkles on the nose, twist the mouth, or squeezes the eyes.
Based on above information b is the correct option as it is indicative of pain.