What sampling procedure groups participants according to preselected criteria relevant to a particular research question

A researcher conducts a case study entitled “Effect of Study Circle on Moral Attitudes of Filipino Senior High School Students”, wherein ten (10) participants are selected from each Senior High Public Schools in Pasig City and were further divided into subgroups according to their grade levels and gender. What sampling procedure was used?

What sampling procedure is typically used by journalists who need quick and easy access to people from their population of interest?

A researcher who wanted to study how people with genital herpes cope with their medical condition has been referred by the first interviewee to another potential subject. What sampling procedure is employed

A case study that seeks to examine the financial and economic lives of Philippine indigenous people was conducted by interviewing 16 participants from three selected indigenous communities in the Philippines with the following characteristics: four elderly (2 males, 2 females), four adolescents (2 male and 2 female), and the remaining eight informants were household heads and their spouses. What sampling procedure was used?