The supremacy clause plays a key role in disputes among states, or between states and the national government because

The supremacy clause in Article IV of the constitution is the clause in the constitution and it affirms that "Constitution is the supreme law of the land". This gives the federal government more power than the states to resolve issues between states and bring them together. The Founders also wanted to give the final power to federal government and had the same objective while forming the clause.

is this an essay or multiple choice

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.