Each of the following is a duty of a u. s. marshal except

c. troops marched forward in close formation against newer, more accurate weapons

while it was true that the cotton gin reduced the labor of removing seeds, it did not reduce the need for slaves to grow and pick the cotton.

explanation:

before eli whitney's invention of the cotton gin, picking and cleaning cotton was a slow, labor-intensive job. workers, usually slaves, had to pick the seeds from the cotton fibers by hand. this invention made it possible to grow large amounts of cotton on big farms and make money.

d. it gave farmers a way to organize for more political power