Why Is Highly-Structured Research and Analysis Preferred for Causal Research

Why is highly-structured research and analysis preferred for causal research goals?

A) Highly-structured research and analysis are the preconditions for discovery.
B) As there are so many possible variables in marketing situations, a more complex and highly-structured approach yields better results.
C) Less structured approaches can be used, but they end up being far more expensive.
D) Causal research goals require sophisticated techniques that are beyond the capacity of all but professionals who can construct the highly structured research and analysis.