Answer: c) 10
In many ways, our present agricultural system is structured such that we are, in effect, eating oil. According to Michael Pollan, it takes 10 calories of fossil fuel energy just to produce one typical calorie of food energy. He goes on to point out that "It’s estimated that the way we feed ourselves (or rather, allow ourselves to be fed) accounts for about a fifth of the greenhouse gas for which each of us is responsible." His argument is that gardens are the ultimate way to not only lower the energy required to produce our food, but also to foster community, change the way we relate to the planet, and heal both our minds and bodies.
Source: NY Times