This question is essentially asking what happens to sympathetic and parasympathetic efferents in the setting of hypovolemia/dehydration. In this setting, there would be lower blood pressure and thus this would cause reduced firing of the carotid baroreceptors, ultimately leading to feedback which stimulates the sympathetic nervous system (to increase heart rate and cause peripheral vasoconstriction in order to compensate for hypovolemia) while also inhibiting the parasympathetics.