In What Way Was the Labor System Used to Construct

In what way was the labor system used to construct the Erie Canal a portent of the future?

A) The use of immigrant labor to build the canal set a pattern for later canal and railroad construction.
B) By using heavy mechanical equipment to dig the canal, the project signaled the end of the need for cheap unskilled labor.
C) Access to the canal resulted in an increase of products created by nearby residents through the labor-intensive putting-out system.
D) The greatest labor source for canal construction was composed of free blacks and runaway slaves from the South.