The nature versus nurture question asks: A. How do people's brains develop?
B. How much effect does nature have on our development?
c. Can better nurturing improve development?
D. What is the interaction between genes and environment?

D. What is the interaction between genes and environment?

Explanation:

"Nature versus nurture" is a complex and lasting debate that seeks to answer questions about the results on the interaction between nature and nuture in our body and mind. Many believe that this interaction does not exist and that we are shaped, solely, by one of them. However, many researchers believe that we are shaped by the union of these two elements, which not only interfere in our physical nature, but also in our peronality and behavior.

i believe the answer is:   psychological  experiment

in this experiment, wilhelm wundt became the first person that implement scientific method in analyzing the pyschological phenomenon.

due to this result, wilhelm wundt also able to make psychology to be acknowledged as a separate scientific field from biology.