Kept the articles from being ratified for four years. a)disputes over land issues b)selfishness on the part of maryland c)jealousy over representation in the congress d)lack of communication due to the war e)miscommunication on the part of pennsylva

no , per capita income is not a true measure of the development because: -it only tells us about average income not how income is distributed among the people.it only give us an idea of the economic aspect.it is only at the qualitative basis.moreover, income is not only the way of development other factors are also as much as important as income.

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.