"When a marketing researcher wants to interview teenagers between the ages of 16 -19 about what types of music they prefer, and asks the researchers to go to a shopping mall and ask teenagers if they own at least 100 music CDs in order to select her interview sample, and then asks shoppers who qualify for this screening question to suggest the names of two of their male friends who own at least 100 music CDs to see if they want to participate in the study as well, what type of sampling procedure is being used

Snowball sampling is the sampling procedure used for this particular study.

Explanation:

In the initial stage of snowball sampling, individuals are discovered and may or may not be selected through probability methods.This group is then used to refer the researcher to others who possess similar characteristics and who, in turn, identify others.

It is also especially appropriate for some qualitative studies. Snowball sampling sampling uses a referral approach to reach particularly respondents who are difficult to identify and contact.  

answer; dogs;

answer(b) partnership';