OG34 WHICH 与THAT用法

34. A report by the American Academy for the Advance­ment of Science has concluded that much of the currently uncontrolled dioxins to which North Ameri­cans are exposed comes from the incineration of wastes.

(A)  much of the currently uncontrolled dioxins to which North Americans are exposed comes

(B)  much of the currently uncontrolled dioxins that North Americans are exposed to come

(C)  much of the dioxins that are currently uncon­trolled and that North Americans are exposed to comes

(D)  many of the dioxins that are currently uncontrolled and North Americans are exposed to come

(E)   many of the currently uncontrolled dioxins to which North Americans are exposed come

请问C中,如果much改成many,这句话是不是就对了? and that North Americans are exposed to 是不是等于to that noth Americans are exposed? to that 结构好象是错误的吧,只有见过to which啊.

求教!!

我觉的C本身的结构就不合理，that are currently uncon­trolled and that North Americans are exposed to 作为定语从句是不是很罗嗦？本来没有必要把uncontrolled 非变成一个定语从句的，用过去分词即可，而且本来uncon­trolled 和that North Americans are在句子里，虽然都是限定词，但它们之间是一层修饰另一层的关系，而不是并列的关系，C就把这层关系篡改了。不知道楼主意下如何?