Answer:
c. to understand which variables are the cause and which variables are the effect of a phenomenon.
Step-by-step explanation:
Descriptive research is a research where the population is described or the situation is to be studied. Here the focus is to answer the questions in terms of how, what, where, and when instead of why.
So as per the given optiosn, the option c is incorrect as the option a, b and d represent the descriptive research
So the left option i.e. option c is to be choosen