The owner of an apartment complex has a special promotion going that pays any tenant that refers a person that becomes a tenant $50.00 cash and a $50.00 gas card. This is:

Marketing and advertising strategies seek to impact the largest number of subjects with the lowest amount of cost, thus maximizing profits by expanding the customer base, for this purpose various strategies are developed, including referral plans, which they consist of converting the current customers of our product into advertising agents of this product, seeking to convince them to receive recommendations from potential customers or that they themselves refer our product or service to one of their relatives, all in exchange for some kind of bonus or incentive, with which it is possible to impact in multiple social circles with a much lower cost than a media advertising campaign

Answer

This is a marketing strategy called referral plan