Answer:
B .Without a labor force, the city came to a halt
Step-by-step explanation:
As Patricians placed unjust economic and cultural restrictions on Plebeians they decided to move to the mountains which was beyond the Anio and they refered as the Sacred Mount (Morey). When Patricians understood that there is threat to city if Plebeians will actually leave Rome because not they were great soldiers but also act as skilled craftsman and producers who render services to the Rome, city will not survive and come to halt.
In order to protect Rome from such crisis of labour and soldier, Patricians agreed to litsen the demands made by Plebeians to live debt free life.