Final answer:
Social couponing is a sales trend that refers to Groupons and requires online or social media action, usually involving group buying and digital sharing, distinct from traditional coupon distribution methods.
Step-by-step explanation:
Social couponing is one of the hottest sales promotion trends today, and it refers to option C) Groupons. This term involves the use of social media or other online platforms to distribute coupons or promotional deals, often requiring participants to join a group or initiate some social action to activate the deal.
Examples include deals where a certain number of people need to purchase the coupon for it to become valid, leveraging the power of group buying and digital sharing.
Regarding the scenarios provided with the envelopes and coupons, these would constitute a type of game or promotion but not specifically social couponing as it lacks the digital or social media aspect typically involved in Groupons.
Economists might refer to getting a "good deal" on a product as consumer surplus, which is the benefit or excess satisfaction received by consumers because they're able to purchase a product for a price that is less than the maximum they're willing to pay.