A survey was carried out on the death rate of those who were infected by SARS,   （）      were surprising.

题目解析[D]：这道题考察的是非限制性定语从句的用法。主句为："A survey was carried out on the death rate of those who were infected by SARS, ______ were surprising." 从句需要填入一个关系代词来引导定语从句，修饰先行词"those"。由于从句是非限制性定语从句，所以要使用"which"。选项D "the results of which" 正确地引导了从句，并且修饰先行词"those"，表达的意思是"这些结果"。