Will give 10

which of the following was an effect of the land ordinance of 1785?

a. it encouraged settlers to fully populate the thirteen states.
b. it brought money to the nation through the sale of public lands.
c. it allowed slavery to spread into the northwest territory.
d. it limited the growth of schools and public education.

B. It brought money to the nation through the sale of public lands. None of these are excellent, but that's the best choice. 
The Land Ordinance of 1785 basically was a way for the federal government to gain money by selling land to settlers in the undeveloped WEST, so it had nothing to do with the population of the 13 states. As mentioned, the government partitioned the land and sold it to people, making them money. Northwest territory wasn't really a thing yet, but when it did become a thing, slavery wasn't allowed, so that's blatantly wrong. And education was established and funded similarly to how it was in the original states. 
If you asked me without the choices, I would just tell you it was a means for expansion to the west, but money is the clear choice here.