Answer:
A) the sun rising in the morning
Explanation:
In biology, hibernation refers to a physiological state where a plant or animal is metabolically inactive in the winter period (characterized by extreme cold). As far as the animal or plant is concerned, the cold weather during winter is an adverse condition, hence, they undergo hibernation in order to conserve their energy.
According to this question, arousal or wakening from hibernation would be triggered in the presence of heat source, which in this case is the SUN RISING IN THE MORNING.