What's the biggest difference between the first and second green revolution in America?
A.
The first green revolution is to improve the food output while the second is not.
B.
The second green revolution is based on the theory of inserting genes while the first depends on that of crossbreeding.
C.
The technology that is used in the second green revolution has much more enormous potential than that of the first's.
D.
The second green revolution has caused harm to the environment while the first has not.