Which innovation directly led to the development of the first city-states? O A. Levees
O B. The wheel
C. The calendar
D. Astronomy

O A levees not sure my answer 1

A guild is an association of artisans or merchants who oversee the practice of their craft in a particular town. The earliest types of guild were formed as confraternities of tradesmen. They were organized in a manner something between a professional association, trade union, a cartel, and a secret society.

After researching each word , I would say (4) Labor unions