Final answer:
The correct answer to the question is 'subtly,' which describes a gentle and discreet way of correcting behavior through nonverbal cues, unlike loud, forceful, or angry responses.
Step-by-step explanation:
A quiet grunt or a quick shake of the head can be used subtly to correct behavior. The correct answer is A) Subtly. This means that the action is done in a manner that is not aggressively noticeable or forceful but rather gently or delicately that is sophisticatedly effective.
A loud, forceful, or angry response can be too aggressive and often counterproductive when attempting to correct someone's behavior, especially in situations requiring tact and discretion. Instead, subtle nonverbal cues can provide feedback without creating hostility or embarrassment.