In the 1830s, Cyrus McCormick improved grain farming when he patented his
A. tractor.
B. thresher.
C. plow.
D. reaper.
E. mower
Answer: D
In the 1830s, Cyrus McCormick improved grain farming when he patented his
A. tractor.
B. thresher.
C. plow.
D. reaper.
E. mower