Answer:
C) Club membership program
Explanation:
When Southwest Airlines offers free future flights to their customers, they are using club membership program. These programs are used to make stronger relationships with the customers. These type of programs are initiated from the CRM (Customer Relationship Management) departments of an organization. Companies want their customers to purchase their products and services over and again in the future, therefore, they offer them some incentives and bonuses in order to persuade them for using their products in the future.
