Final answer:
An individual joining a group because of a specific cause they are passionate about is an example of purposive incentives, which are motivated by a commitment to a group's goals and causes.
Step-by-step explanation:
If an individual joins a group because there is a specific cause they feel strongly about, this would be an example of purposive incentives. Purposive incentives lead people to join and contribute to a group because they support the group's goals and are passionate about the causes the group champions. For instance, members may join the American Civil Liberties Union (ACLU) due to their commitment to protecting civil liberties, irrespective of their personal views about the expressions of those liberties.
Conversely, solidary incentives motivate people to join groups for the social rewards, such as pleasure from interacting with like-minded individuals. Meanwhile, material incentives refer to tangible benefits like discounts or insurance, often used by organizations such as AARP to attract members.