Huong creates a campaign to find resources to offer an advanced economics class at her school. She contacts local businesses and asks if they can donate money or materials for the class. One business tells Huong that they have also been approached about donating resources to the school's music program. Unfortunately, they have the resources to support only one program, not both. The school program the business does not supp an example of a decision tree. Oan explicit cost. Oan economic action. an opportunity cost.