The correct answer is "A system of plantations developed in the southern colonies."
Although you forgot to include the bow with the information, we can say the following.
The way in which the factors listed in the box affected the economic development of the southern colonies was "A system of plantations developed in the southern colonies."
The factors listed in the box were: Large amounts of flat land, rich soil, and long summers and mild winters.
This system of plantations was the base and foundation of the southern economy that needed slaves to grow the kinds of crops needed to export them to Europe and to trade with other colonies. That is why southerners supported slavery.
