How Did John Deere's Steel-Tipped Plow Change American Agriculture

How did John Deere's steel-tipped plow change American agriculture?

A) It cut in half the labor needed to till the soil for planting.
B) It facilitated crop rotation which allowed each acre under cultivation to produce greater yields.
C) It made farming so efficient that more people could afford to buy land and start farms.
D) It persuaded Congress to subsidize the development of other farm technology.
E) It could harvest wheat seven times as fast and with fewer work than previously.