How has modernization changed agriculture since the great leap forward?

The correct answer for the question that is being presented above is this one: "d. all of the above." Modernization changed agriculture since the Great Leap Forward by having no more communal farms, increased production, contract responsibility system.

Here are the following choices:
a. no more communal farms
b. increased production
c. contract responsibility system
d. all of the above

Ithink the answer is b

Tropical climate is experienced in the nothern countries of south america