In 1900, 40% of the US labor force worked in agriculture. A hundred years later, in 2000, only 2% worked in agriculture. What is an important reason for this change?
A.
There was not enough good farmland left.
B.
Congress passed a law restricting the number of farmers there can be.
C.
Improved technology meant that the country needed fewer farmers to meet its needs.
D.
Large numbers of farmers left the US for countries where they were needed.