Answer:
to determine the casual relationships between social elements (option b).
Explanation:
When we are talking about qualitative research, we are talking about research that deals less with calculations or even no calculations at all (or we can say that it deal less with numerical values), and this type of research involves more or seek to extract information more from how people behave. Qualitative research can be in form of questionnaires, observations and so on.
And, talking about the quantitative type of research we are talking more about the collection of data that deals more with calculations (numbers).
So, the common goal of qualitative and quantitative research is that of option 'b'; ''to determine the casual relationships between social elements".