Solidary incentives and purposive incentives are the correct answers, respectively.
According to the American sociologist Mancur Olson, individuals do NOT join groups for rational means but through incentives. These incentives can be either solidary, material or purposive. Material incentives are understood as economic benefits or opportunities that will come afterwards. Solidary incentives, on the other hand, include companionship, a sense of belonging that will come with the pleasure of associating together. Purposive incentives are related to the ethical beliefs and principles that the person holds.
