Why Were Lines Between Social Sciences Unclear When They First

Why were lines between social sciences unclear when they first developed?

A) The backgrounds of early social scientists were diverse,and they often conducted work in multiple disciplines.
B) Early social scientists,who were educated as physicians,were reluctant to leave their medical school posts.
C) Social scientists lacked research topics and had to turn to other disciplines for ideas.
D) High degrees of social cohesion among social scientists made them reluctant to split apart.