Answer: I believe it would be A. People huddling together on New Year's Eve in Times Square.
Step-by-step explanation:
This is Google's definition of Kleptothermy:
Kleptothermy is any form of thermoregulation by which an animal shares in the metabolic thermogenesis of another animal. It may or may not be reciprocal, and occurs in both endotherms and ectotherms. Its most common form is huddling.
Hope this helps!