Here's a problem to solve: In Australia, mid-day temperatures can soar to over 110°F (43°C). In order to keep their bodies cool, kangaroos lick their arms, coating them with a thick layer of saliva. As the saliva evaporates, it acts as a cooling mechanism and lowers the kangaroo's body temperature. Which term best describes this activity?

Among the 4 following options, which is the correct answer?

- A: natural selection
 
- B: defense mechanism
 
- C: structural adaptations
 
- D: behavioral adaptations
 