The Shi’a Muslims did not accept the rule of the first three caliphs because the caliphs a) rejected the five pillars of faith..
b) didn’t receive revelations from the angel Gabriel.
c) were not related to Muhammad.

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.

answer; the civil right act of 1964;