Yes, I am sure. The Middle Colonies, such as New York and Philadelphia, developed into large cities primarily because they were situated at key ports that facilitated trade. These ports allowed for the import and export of goods, which in turn attracted merchants, settlers, and a diverse population, contributing to urban growth.
While slavery and workforce participation, including women in commerce, played roles in the broader economic system, the specific reason for the growth of large cities was their strategic locations for trade. Thus, the response about key ports and trade is the most accurate.