Answer: C. Gravel
Gravel has the highest permeability.
A staple food<span> is one that is eaten regularly and in such quantities as to constitute the dominant part of the diet and supply a major proportion of energy and nutrient needs. ... Just 15 </span>crop<span> plants provide 90 percent of the world's </span>food<span> energy intake, with three rice, </span>maize<span> and wheat - making up two-thirds of this.</span>
