Dentify which of these types of sampling is used: random, systematic, stratified, cluster, or convenience. a. Students in a larger lecture course are divided into freshmen, sophomores, juniors, and seniors. 20 students are randomly selected from each group. b. Students in a large lecture course are numbered. A sample is formed by selecting every 10th number in the list. c. Students in larger lectures are enrolled in 15 lab sections. 3 sections are randomly selected, and then select all the students from those three sections.