I think that the best answer is "c. an incentive to bring their ideas to market" - you can see that through the statement of "<span>the opportunity to profit from their ideas"- an opportunity to profit is an incentive to work and in the case of the creators - to bring their ideas to market.
However, an opportunity to profit is not a guarantee that one will profit - so for example option a) is wrong. </span>
Expansion lead to economic promise and fueled the manifest destiny
Explanation:
The north contained a lot of abolitionists while the south was commonly pro-slavery, this increased sectional tension because each side wanted to see their ideals extended into the west.
The best example of people modifying their environment is the construction of cities, where homes and offices for working are built as well as plantation to provide food to community.
