Answer:
The daily release of hot water into the pond from a local factory.
The answer is serotonin. Serotonin is a significant chemical neurotransmitter in the human body. Serotonin that is used in the brain must be made within it. It is believed that serotonin can touch mood and social performance, hunger and ingestion, slumber, reminiscence and sensual desire and purpose.
The source of the centripetal force for this action is tension
Hope that helps :)