[单选,材料题] By selling special coffee at a coffee cafe, the students are________

回答下面的题目
    Every morning, kids from a local high school are working hard．They are making and selling　special coffee at a coffee oaf6．They are also making a lot of money．These students can make up to twelve hundred dollars a day．They are selling their special coffee to airplane passengers．After the students get paid, the rest of the money goes to helping a local youth  project．These high school students use a space in the Oakland airport．It is usually very crowded．Many　people who fly on the planes like to drink the special coffee．One customer thinks that the coffee costs a lot but it is good and worth it．Most customers are pleasant but some are unhappy．They do not like it if the coffee cafe is not open for business．The students earn $6.10 an hour plus tips．They also get school credit while they learn how to　run a business．Many of the students enjoy the work although it took some time to learn how to do it．They have to learn how to steam milk, load the pots, and add flavor．It takes some skill and　sometimes mistakes are made．The most common mistake is forgetting to add the coffee．

Based on the passage, it seems that the purpose of the cafe is to________