The right answer is "A.Parasympathetic nervous system".
It is called the parasympathetic nervous system that is part of the autonomic nervous system whose neurons are located in the brainstem or sacral medulla, segments S2, S3 and S4. It is responsible for stimulating actions that allow the body to respond to situations of calm and relaxation. These actions are: deceleration of heart rate, decrease in blood pressure, decrease in adrenaline and blood sugar.