Using the most reliable information available, how much of the earth's land surface is used for agriculture today?

ANSWER:

Satellite imagery suggests that almost 40% of the land surface of the earth is used for agriculture today.

EXPLANATION:

Agriculture is the main stay of many economies of the world and there are around 570 million farmers on the Earth today who make use of the land for agricultural purposes. The land is used for growing crops of different varieties and in different seasons. A wide range of techniques are put to use for growing crops on the agricultural land. The farmers make use of the best means to ensure that the crops yielded are of good quality and also to get a high yield.

Ithink its b but i'm not sure.