In a study of energy flow, the following data were collected:

Each human requires 55 grams of protein per day.
An acre of soybeans produces 200,000 grams of protein per year.
A cow grazing on one acre of land produces 19,000 grams of protein per year.

Based on these data, an acre of land would support:

10 humans per year on a diet of soy, or 0.9 human per year on a diet of beef.

What is the statements that best explains these relationships in terms of energy transfer?