Creswell and Plano Clark Identified Broad Types of Research Situations

Creswell and Plano Clark identified broad types of research situations that are especially well suited to mixed methods research. What is one of these types of research situations?

A) Concepts are new and poorly understoodand there is a need for quantitative exploration.
B) The qualitative results are puzzling and difficult to interpret and quantitative data can help to explain the results.
C) The findings from both approaches can be greatly enhanced with a third source of data.
D) Neither a qualitative nor a quantitative approach by itself is adequate in addressing the complexity of the research problem.