The Jones family of Jacksonville would like to live more sustainably by reducing their fossil fuel use. They already carpool and have reduced their electricity use. In addition to what they are already doing, which of the following would be most helpful in further reducing their fossil fuel use? Removing most of the grass in their yard and replacing it with a vegetable garden.
Consuming more farm-raised beef and reducing the amount of vegetables they eat.
Fertilizing their yard more frequently and watering to encourage grass to grow.
Planting exotic shade plants in their yard and hiring a lawn care company to tend them.

The kidney filters potentially toxic substances in the blood, and thus “clears” the blood of those substances. this clearance function is dependent upon and proportional to the diffusion gradient of the substance across filtering capillaries, i.e. if the concentration of the substance is doubled, twice as much will be cleared from each ml of blood that is filtered. suppose that the body produces a constant amount of a substance x per unit of time. the kidneys eliminate substance x at a rate directly proportional to the concentration of the substance and the volume of blood cleared each minute (c): elimination = c × [x], where [x] is the steady-state concentration of substance x. imagine an individual with an initial concentration of x equal to [x]0 who develops kidney disease. her baseline clearance c0 drops to one half of the original (½c0). what is the new steady state concentration of x? (for simplicity, assume that substance x is 100% filtered by the kidney).