Answer: Responding to the outer environment.
Step-by-step explanation:
There are many characteristics of human beings that is required to survive. Out of all those one of them is responding to the outer environment.
The response of the outer environment can be any response by the body. Suppose the environment outside is cold then the body starts shivering and when the environment outside is hot then the body starts sweating or panting.
This is how the body responds to the outer environment.