单选题 Living in the western part of the country has its problems, ______ obtaining fresh water is not the least.
A. with which B. for which C. of which D. which

【正确答案】 C

【答案解析】[解析] 正确答案为C项。从句的正常语序应为obtaining fresh water is not the least of which (of its problems)。介词of表示“在……(同类人或物)中”，例如：He is the most diligent of the boys. 他是男生中最勤奋的。