Living in the central Australian desert has its problems,______ obtaining water is not the least.a、for which b、to which c、 of which d、 in which

Living in the central Australian desert has its problems,______ obtaining water is not the least.a、for which b、to which c、 of which d、 in which
Living in the central Australian desert has its problems,______ obtaining water is not the least.
a、for which
b、to which
c、 of which
d、 in which

Living in the central Australian desert has its problems,______ obtaining water is not the least.a、for which b、to which c、 of which d、 in which
选C.of which 代替of the problems .
of 有“其中之一”的意思.

C
从句部分 是 获取水不是一个小问题
前面部分说 ... has its problems，有不只一个问题
所以后面提到的水 只是 one OF the problems
所以从句用 of which 连接