On a time crunch, easy mc question

A teacher surveys every 3rd student in their class list about her teaching style during elearning. This type of sampling is called... Stratified random sampling Systematic random sampling Simple random sampling Cluster random sampling Question 16 (1 point) A large university has 15 buildings in which classes are run. Each of these buildings hosts 5 classes per day. In order to collect information about students taking different classes, the university selects 10 classes from the 75. Then, it interviews everyone in that class. This is an example of: Stratified random sampling Multi-stage random sampling Systematic random sampling Cluster random sampling