阅读理解
阅读下列短文，从每题所给的A、B、C和D项中，选出最佳选项，并在答题卡上将该项涂黑。
A
Many people think of dirt as being, well, dirty! Parents often tell their children not to play in dirt or to get it on their clothes. And there are good reasons to be wary ─ soil often contains bacteria, parasites and pollutants that can make people sick. With so many risks, it is no surprise that many people find geophagy ─ literally the eating of earth or soil ─ unappetizing.
Yet, geophagy is actually a relatively common practice in many parts of the world. Since people tend to be very selective about which soils they eat, the practice has also created a thriving industry. In Nigeria, the village of Uzalla annually processes over 500 tons of its prized soil for sale and consumption in markets hundreds of kilometers away. Geophagy also has a long history in the U.S., where some eat clay and ship packages of it to
