The Reforms of Cleisthenes - the tribes  Athenian citizen storming the Acropolis, from The Greeks documentary
The 'democratic' reforms of Cleisthenes were a highly complicated revision of tribal and religious associations that had endured for centuries. Above all else, they were an attempt to make the different factions and regions of Athens into one people, with a popular assembly, and the necessary institutions to make that assembly work. Link: https://www.pbs.org/empires/thegreeks/background/10a.html
I think the answer is between b and c. But the answer that I heard of in history class would be C. The fact that immigrants took away high paying jobs from union members.
