How Did John Deere Change American Agriculture

How did John Deere change American agriculture?

A) He invented a steel-tipped plow that made tilling much easier and less time consuming.
B) He introduced crop rotation which allowed each acre under cultivation to produce greater yields.
C) He created a conglomerate of farmers which gave them greater control over the market.
D) He persuaded Congress subsidize farmers during bad years.
E) He developed a reaper that could harvest wheat seven times as fast and with fewer works than previously.