A doctoral learner has decided to do a case study for his/her proposed dissertation research study topic because it is believed to be the best approach to address the research questions. The researcher's choices of data sources for this particular study are to conduct interviews, to conduct observations, and to conduct focus groups. Will these data sources generate the breadth and depth of the data necessary for this design? Why or why not? What challenges might the researcher encounter in collecting data from these sources? Explain.