但是这个错是不是错在分号后面的it指代错呢？ 选项B中的one是指前面的principle吗？
Yes, it's not clear what it refers to. Strictly speaking, "one" refers to a principle but not the "a new prnciple" in the first part of the sentence. It could have been written as "but a principle that" , but for the sake of being concise, the phrase is replaced with "one". | 
