Answer with explanation and don't make random guess

Random versus non-random sampling Ky is a visual artist who also runs artist cooperatives across the northeast. He is interested in whether implementing a self-service checkout kiosk would affect the sales of art supplies. In half of the locations, he replaced the traditional checkout counters with self-service kiosks and measured the number of sales. He measured sales from all of the stores. What type of sampling technique did he use? O Simple random sample Systematic sample O Stratified sample O Cluster sample O Convenience sample O Snowball sample Judgment sample No sample was used this was an example of a census