What Was the Significance of the Invention of the John

What was the significance of the invention of the John Deere steel plow?

A) It allowed farmers to cultivate tough prairie soils.
B) It lowered the cost of steel plows.
C) It helped farmers plow loose soil in half the time of a cast-iron plow.
D) It allowed farmers to plow by hand without the aid of a farm animal.
E) It allowed farmers to plow more accurately than cast-iron plows.