The greatest risk occurs in overpopulated communities and refugee settings characterized by poor sanitation and unsafe drinking water. 最大的危險存在于以衛生設施不良和飲用水不安全為特點的人口過密的社區和難民居住地。
A. An overpopulated earth will be unable to sustain its inhabitants. 人口過剩的地球無法維護它上面的居民。