Emily has recently been on the Internet looking for a wedding gown. She is now on the Internet looking for camping supplies they will need for an upcoming trip. She notices display ads for wedding gowns on the camping-related sites. These advertisers are using?

Interest Targeting

Explanation:

Interest segmentation is a technique that allows a company to advertise its products and services, segmenting its customers into interest groups, that is, that company will advertise products and services for you according to the things you show to be interested in.

An example of this can be seen in the question above, where Emily was searching for wedding dresses, so an algorithm in her server realized that she has an interest in wedding dresses, allowing Emily to view ads for those dresses when she was researching visiting websites of camps.

"Remarketing" is the technique you're looking for. This technique targets your computer, not you, and gives you advertisements based on what you were looking at online.