Answer:
A. CR
Explanation:
CR which stands for Cardiorespiratory simply involves all the activities that has to do with heart rate and breathing. The Cardiorespiratory stays balanced under a calm situation but triggers when in fear, danger, excited or anu other activities that can lead to fast heart rate.
Having the feeling where your heart your heart starts pounding and you get a queasy feeling in your stomach because of the quiz announcement is a reaction of Cardiorespiratory.
The announcement trigger the CR.