Final answer:
Hans Selye described 'cooperation with others for the self's sake' as altruism, which is helping others motivated by empathy rather than egoistic reasons.
Step-by-step explanation:
According to Hans Selye, the term he described as the "cooperation with others for the self's sake" is d) Altruism.
In the context of Selye's work on stress, altruism represents a form of prosocial behavior that involves helping others without expecting anything in return. This is seen to be motivated by empathy and can be contrasted with egoistic motivations for helping. Altruism implies that an individual is contributing to the welfare of others without directly benefiting oneself, which can be harmonious with the individual's well-being in the sense of social support and psychological health.