Answer:
organic word-of-mouth
Step-by-step explanation:
Organic word-of-mouth refers to the situation in which a person turns into a promoter for a product providing information about it without any influence because he/she is satisfied with the product and wants to share it with other people. According to this and considering that Beth found the right sunscreen and she decided to tell all her close friends about how good the product is, this is an example of organic word-of-mouth.