When Allport (1924) Famously Argued That the Psychology of Groups

When Allport (1924) famously argued that the psychology of groups is really essentially psychology of individuals:

A) it was difficult for the study of the collective self to thrive.
B) the study of the collective self became one of the major topics in psychology.
C) other disciplines that focussed on collectivities were incorporated into psychology.
D) other social phenomena such as language, religion, customs and myth became incorporated into the study of the self.