In his qualitative research project, Chris is conducting an interview study among a white ...

In his qualitative research project, Chris is conducting an interview study among a white supremacist group on campus. Chris initially focuses on the group's friendship networks to determine membership and participation. In the course of his research, however, he finds out there are university administrative officials who are also affiliated with this group. Chris then decides to expand his sample to include these university officials and other students that they interact with. This sampling method which evolves and directs the sampling in certain directions is known as
 
  a. convenient sampling.
  b. snowball sampling.
  c. purposive sampling.
  d. theoretical sampling.
  e. quota sampling.