阅读理解。阅读下列短文, 从给的四个选项 (a、b、c和d) 中, 选出最佳选项。
without proper planning, tourism can cause problems. for example, too many tourists can crowd public places that are also enjoyed by the inhabitants of a country. if tourists create too much traffic, the inhabitants become annoyed and unhappy. they begin to dislike tourists and to treat them impolitely. they forget how much tourism can help the country's economy. it is important to think about the people of a des
