Nearly 50% of the land on our planet is currently used for agriculture, with very little more agriculturally usable land available. If everyone on the planet had an ecological footprint the size of the average citizen of the United States, then .

We'd need at least two Earths more to feed and help everybody

Explanation:

An ecological footprint calculates how much land and resource use it takes to support your lifestyle. It measures humans demand on nature. There is evidence that human activities are directly contributing to global environmental changes. The indicators used in this activity are one way of estimating the impact humans have on the planet.

The ecological footprint size of the average citizen of the United States is quite much this gives a rise of more demands on nature. Which implies more lands mass would be needed.

E. We would need at least two more planet Earths to feed and support everyone

Explanation:

Ecological footprint talks about the amount of nature needed to support an individual or economy. It measures individuals demand for plant based food, fiber, livestock and fish product. If everybody have the demand for nature like an average American citizen which is quite large, we would need atleast 2 more planet earth to support everyone demand for food and all given size of agriculturally usable lands on earth and the ecological footprint of an average America citizen.