Answer: The correct answer is Stress mediator.
Explanation: A stress mediator helps the individual experiencing stress to deal with his stressors in a more adaptative manner.
Human beings have their own neural and endocrine mechanisms that pose as stress mediators. Support groups, a network of friends, the family can also serve individuals as providers of stress mediators.
In this particular case, Nelson has a large network of friends who help him deal with his stressors. The support his friends provide is a Stress mediator.